Is there a name for this chart - sort of a cross between a pie chart and a mekko plot Is there a name for this sort of chart below (sourced from New Zealand's Ministry of Business, Innovation and Employment, for whom I work but I was not involved in creating this plot)?  It consists of rectangles where the area is proportional to a variable, and resembles a sort of cross between a pie chart, a mosaic plot and a mekko plot.  It is perhaps closest to a mekko plot but has the complication that we are not working with columns but a more complex jigsaw.
The original looks a little better as there are white borders between the rectangles for each region.
Surprisingly, it actually strikes me as not too bad a statistical graphic, although it could be improved through better use of colour mapped to something meaningful.  A powerful interactive version showing the US 2011 budget has been used by the New York Times.
An interesting challenge is to think of an automatic algorithm to draw one and make it look reasonable too.  The rectangles need to be allowed to have different aspect ratios, within an acceptable range.

 A: Edit / addition
I have since discovered that the treemap package gives a much better result than the map.market() function mentioned (and adapted) below; but I'll leave my answer in for historical reasons.
Original Answer
Thanks for the answers.  Building on the flowing data link provided by @JTT but disliking the need to tweak by hand in Illustrator or Inkscape just to get a reasonable graphic, I tweaked the map.market() function in Jeff Enos and David Kane's portfolio package to make it more user-controlled, the labels vary by rectangle size, and avoid red-green contrasts.  Example usage:
library(portfolio)
library(extrafont)
data(dow.jan.2005)

with(dow.jan.2005, 
    treemap(id    = symbol,
        area  = price,
        group = sector,
        color = 100 * month.ret,
        labsc = .12,  # user-chosen scaling of labels 
        fontfamily="Comic Sans MS")
    )


For what it's worth, I also agree with @NickCox that in the example in my original question a dot plot is superior.  Code of my adapted treemap() function follows.
treemap <- function (id, area, group, color, scale = NULL, lab = c(group = TRUE, 
    id = FALSE), low="red", middle="grey60", high="blue", main = "Map of the Market", labsc = c(.5, 1), print = TRUE, ...) 
{
    # Adapted by Peter Ellis from map.market() by Jeff Enos and David Kane in the portfolio package on CRAN
    # See map.market for the original helpfile.  The changes are:
    # 1. low, middle and high are user-set color ramp choices
    # 2. The font size now varies with the area of the rectangle being labelled; labsc is a scaling parameter to make it look ok.
    #    First element of labsc is scaling parameter for size of group labels.  Second element is scaling for id labels.
    # 3. ... extra arguments to be passed to gpar() when drawing labels; expected use is for fontfamily="whatever"
    require(portfolio)
    if (any(length(id) != length(area), length(id) != length(group), 
        length(id) != length(color))) {
        stop("id, area, group, and color must be the same length.")
    }
    if (length(lab) == 1) {
        lab[2] <- lab[1]
    }
    if (missing(id)) {
        id <- seq_along(area)
        lab["id"] <- FALSE
    }
    stopifnot(all(!is.na(id)))
    data <- data.frame(label = id, group, area, color)
    data <- data[order(data$area, decreasing = TRUE), ]
    na.idx <- which(is.na(data$area) | is.na(data$group) | is.na(data$color))
    if (length(na.idx)) {
        warning("Stocks with NAs for area, group, or color will not be shown")
        data <- data[-na.idx, ]
    }
    zero.area.idx <- which(data$area == 0)
    if (length(zero.area.idx)) {
        data <- data[-zero.area.idx, ]
    }
    if (nrow(data) == 0) {
        stop("No records to display")
    }
    data$color.orig <- data$color
    if (is.null(scale)) {
        data$color <- data$color * 1/max(abs(data$color))
    }
    else {
        data$color <- sapply(data$color, function(x) {
            if (x/scale > 1) 
                1
            else if (-1 > x/scale) 
                -1
            else x/scale
        })
    }
    data.by.group <- split(data, data$group, drop = TRUE)
    group.data <- lapply(data.by.group, function(x) {
        sum(x[, 3])
    })
    group.data <- data.frame(area = as.numeric(group.data), label = names(group.data))
    group.data <- group.data[order(group.data$area, decreasing = TRUE), 
        ]
    group.data$color <- rep(NULL, nrow(group.data))
    color.ramp.pos <- colorRamp(c(middle, high))
    color.ramp.neg <- colorRamp(c(middle, low))
    color.ramp.rgb <- function(x) {
        col.mat <- mapply(function(x) {
            if (x < 0) {
                color.ramp.neg(abs(x))
            }
            else {
                color.ramp.pos(abs(x))
            }
        }, x)
        mapply(rgb, col.mat[1, ], col.mat[2, ], col.mat[3, ], 
            max = 255)
    }
    add.viewport <- function(z, label, color, x.0, y.0, x.1, 
        y.1) {
        for (i in 1:length(label)) {
            if (is.null(color[i])) {
                filler <- gpar(col = "blue", fill = "transparent", 
                  cex = 1)
            }
            else {
                filler.col <- color.ramp.rgb(color[i])
                filler <- gpar(col = filler.col, fill = filler.col, 
                  cex = 0.6)
            }
            new.viewport <- viewport(x = x.0[i], y = y.0[i], 
                width = (x.1[i] - x.0[i]), height = (y.1[i] - 
                  y.0[i]), default.units = "npc", just = c("left", 
                  "bottom"), name = as.character(label[i]), clip = "on", 
                gp = filler)
            z <- append(z, list(new.viewport))
        }
        z
    }
    squarified.treemap <- function(z, x = 0, y = 0, w = 1, h = 1, 
        func = add.viewport, viewport.list) {
        cz <- cumsum(z$area)/sum(z$area)
        n <- which.min(abs(log(max(w/h, h/w) * sum(z$area) * 
            ((cz^2)/z$area))))
        more <- n < length(z$area)
        a <- c(0, cz[1:n])/cz[n]
        if (h > w) {
            viewport.list <- func(viewport.list, z$label[1:n], 
                z$color[1:n], x + w * a[1:(length(a) - 1)], rep(y, 
                  n), x + w * a[-1], rep(y + h * cz[n], n))
            if (more) {
                viewport.list <- Recall(z[-(1:n), ], x, y + h * 
                  cz[n], w, h * (1 - cz[n]), func, viewport.list)
            }
        }
        else {
            viewport.list <- func(viewport.list, z$label[1:n], 
                z$color[1:n], rep(x, n), y + h * a[1:(length(a) - 
                  1)], rep(x + w * cz[n], n), y + h * a[-1])
            if (more) {
                viewport.list <- Recall(z[-(1:n), ], x + w * 
                  cz[n], y, w * (1 - cz[n]), h, func, viewport.list)
            }
        }
        viewport.list
    }
    map.viewport <- viewport(x = 0.05, y = 0.05, width = 0.9, 
        height = 0.75, default.units = "npc", name = "MAP", just = c("left", 
            "bottom"))
    map.tree <- gTree(vp = map.viewport, name = "MAP", children = gList(rectGrob(gp = gpar(col = "dark grey"), 
        name = "background")))
    group.viewports <- squarified.treemap(z = group.data, viewport.list = list())
    for (i in 1:length(group.viewports)) {
        this.group <- data.by.group[[group.data$label[i]]]
        this.data <- data.frame(this.group$area, this.group$label, 
            this.group$color)
        names(this.data) <- c("area", "label", "color")
        stock.viewports <- squarified.treemap(z = this.data, 
            viewport.list = list())
        group.tree <- gTree(vp = group.viewports[[i]], name = group.data$label[i])
        for (s in 1:length(stock.viewports)) {
            stock.tree <- gTree(vp = stock.viewports[[s]], name = this.data$label[s], 
                children = gList(rectGrob(name = "color")))
            if (lab[2]) {
                stock.tree <- addGrob(stock.tree, textGrob(x = unit(1, 
                  "lines"), y = unit(1, "npc") - unit(1, "lines"), 
                  label = this.data$label[s], gp = gpar(col = "white", fontsize=this.data$area[s] * labsc[2], ...), 
                  name = "label", just = c("left", "top")))
            }
            group.tree <- addGrob(group.tree, stock.tree)
        }
        group.tree <- addGrob(group.tree, rectGrob(gp = gpar(col = "grey"), 
            name = "border"))
        if (lab[1]) {
            group.tree <- addGrob(group.tree, textGrob(label = group.data$label[i], 
                name = "label", gp = gpar(col = "white", fontsize=group.data$area[i] * labsc[1], ...)))
        }
        map.tree <- addGrob(map.tree, group.tree)
    }
    op <- options(digits = 1)
    top.viewport <- viewport(x = 0.05, y = 1, width = 0.9, height = 0.2, 
        default.units = "npc", name = "TOP", , just = c("left", 
            "top"))
    legend.ncols <- 51
    l.x <- (0:(legend.ncols - 1))/(legend.ncols)
    l.y <- unit(0.25, "npc")
    l.cols <- color.ramp.rgb(seq(-1, 1, by = 2/(legend.ncols - 
        1)))
    if (is.null(scale)) {
        l.end <- max(abs(data$color.orig))
    }
    else {
        l.end <- scale
    }
    top.list <- gList(textGrob(label = main, y = unit(0.7, "npc"), 
        just = c("center", "center"), gp = gpar(cex = 2, ...)), segmentsGrob(x0 = seq(0, 
        1, by = 0.25), y0 = unit(0.25, "npc"), x1 = seq(0, 1, 
        by = 0.25), y1 = unit(0.2, "npc")), rectGrob(x = l.x, 
        y = l.y, width = 1/legend.ncols, height = unit(1, "lines"), 
        just = c("left", "bottom"), gp = gpar(col = NA, fill = l.cols), 
        default.units = "npc"), textGrob(label = format(l.end * 
        seq(-1, 1, by = 0.5), trim = TRUE), x = seq(0, 1, by = 0.25), 
        y = 0.1, default.units = "npc", just = c("center", "center"), 
        gp = gpar(col = "black", cex = 0.8, fontface = "bold")))
    options(op)
    top.tree <- gTree(vp = top.viewport, name = "TOP", children = top.list)
    mapmarket <- gTree(name = "MAPMARKET", children = gList(rectGrob(gp = gpar(col = "dark grey", 
        fill = "dark grey"), name = "background"), top.tree, 
        map.tree))
    if (print) {
        grid.newpage()
        grid.draw(mapmarket)
    }
    invisible(mapmarket)
}

A: The question is the name, but how well it works is also open to discussion. 
Here's something much more prosaic as an alternative, a horizontal bar chart. 

What we might want to do with such a graph varies from some grasp of the overall pattern to some scrutiny of individual cases (what about Hawke's Bay, and so forth). I'd assert that both are easier with a bar chart. Small details are that I use lower case in titles and names where easy and don't repeat the % sign. I've roughly imitated the colour coding without finding out what it means, so that is just as clear, or obscure, as what you copied. 
I suggest that some of the appeal of treemaps lies in their relative novelty. They might work as well as or better than bar charts if there are dozens of names, which can be spread over a two-dimensional area rather than listed in a long column. But for 15 or so names, a bar chart remains a strong competitor in my view. 
I am happy with anyone who prefers a (Cleveland) dot chart here. A vertical bar chart would face the difficulty of placing the region names comfortably. (Just imagine rotating this graph to see that.) I like the idea of giving the numbers too, although conservatives don't like mixing graph and table ideas. 
The graph was drawn in Stata. 
A: That's a treemap, I guess (http://en.wikipedia.org/wiki/Treemapping). 
There are several packages, e.g. in R, that create treemaps. One of the packages is called treemap, and another one is portfolio. For example, Nathan Yau offers a tutorial on how to create a treemap using R (http://flowingdata.com/2010/02/11/an-easy-way-to-make-a-treemap/). 
A: It is a treemap, you can do it easily with Tableau 8 and free Tableau Public, see sample here: http://www.tableausoftware.com/new-features/new-view-types .
You can also see @this URL that Treemap can be combined with Bar Chart
