I may not be able to go to it, but the R community has an annual meeting, useR!, that will be held this year in Ames, Iowa from August 8-10. The web site for this conference (user2007.org) provides some of the details.
Previous conferences were held in Vienna, Austria, which is a bit further away, but also a bit more exotic.
You can find an earlier version of this page on my old website.