OpenBugs vs. JAGS I am about to try out a BUGS style environment for estimating Bayesian models.  Are there any important advantages to consider in choosing between OpenBugs or JAGS?  Is one likely to replace the other in the foreseeable future?  
I will be using the chosen Gibbs Sampler with R.  I don't have a specific application yet, but rather I am deciding which to intall and learn.
 A: I recommend you jags over openbugs for speed reasons. I've tried both on a Linux system, and jags is way faster.
A: I find jags works more smoothly in Linux,  and is easier to setup,  but it does not presently support the spatial analyses that GeoBUGS supports.  So, I use OpenBUGS.
A: BUGS/OpenBugs has a peculiar build system which made compiling the code difficult to impossible on some systems — such as Linux (and IIRC OS X) where people had to resort to Windows emulation etc.
Jags, on the other hand, is a completely new project written with standard GNU tools and hence portable to just about anywhere — and therefore usable anywhere.
So in short, if your system is Windows then you do have a choice, and a potential cost of being stuck to Bugs if you ever move.  If you are not on Windows, then Jags is likely to be the better choice.
A: For those who find this question down the road: there's now also Stan. Stan may one day replace OpenBUGS and JAGS, but it does not yet support all the analyses that these other packages do.
