How can I change the title of a legend in ggplot2? I have a plot I'm making in ggplot2 to summarize data that are from a 2 x 4 x 3 celled dataset.  I have been able to make panels for the 2-leveled variable using facet_grid(. ~ Age) and to set the x and y axes using aes(x=4leveledVariable, y=DV).  I used aes(group=3leveledvariable, lty=3leveledvariable) to produce the plot so far.  This gives me a visualization that is paneled by the 2-leveled variable, with the X axis representing the 4 leveled variable and different lines plotted within the panels for the 3-leveled variable.  But the key for the 3-leveled variable is titled with the 3-leveled variable's name and I want it to be a title that has a character space in it.  How can I rename the title of the legend?  
Things I've tried that don't seem to work (where abp is my ggplot2 object):
 abp <- abp + opts(legend.title="Town Name")
 abp <- abp + scale_fill_continuous("Town Name")
 abp <- abp + opts(group="Town Name")
 abp <- abp + opts(legend.title="Town Name")

Example data:  
ex.data <- data.frame(DV=rnorm(2*4*3), V2=rep(1:2,each=4*3), V4=rep(1:4,each=3), V3=1:3)

 A: You can change the title of the legend by modifying the scale for that legend. Here's an example using the CO2 dataset
library(ggplot2)

p <- qplot(conc, uptake, data = CO2, colour = Type) + scale_colour_discrete(name = "Fancy Title")
p <- p + facet_grid(. ~ Treatment)
p 

EDIT:
Using the example data from above, here is a working solution. I think this mimics the plot that @drknexus is trying to create. As a side note, if anyone can explain why we have to treat V3 as a factor for it to be mapped to the legend, I'd appreciate it.
p <- qplot(V4, DV, data = ex.data, geom = "line", group = V3, lty = factor(V3)) 
p <- p + scale_linetype_discrete(name = "Fancy Title") + facet_grid(. ~ V2)
p 


A: Another option is to use 
p + labs(aesthetic='custom text')     

For example, Chase's example would look like:
library(ggplot2)

ex.data <- data.frame(DV=rnorm(2*4*3),V2=rep(1:2,each=4*3),V4=rep(1:4,each=3),V3=1:3)
p <- qplot(V4, DV, data=ex.data, geom="line", group=V3, linetype=factor(V3)) + facet_grid(. ~ V2)
p + labs(linetype='custom title')

and yield the figure:

