I summarized (with short demos) a few of the talks from the useR! 2012 conference. We are planning one more meetup to cover more talks.
Topics discussed: byte-code compiling, the devtools package, ggmap, Rstudio‘s latest features (projects, git/svn, knitr-markdown integration for reproducible research), cranvas, Simon Urbanek’s talk on interactive graphics in the browser (with Rserve and FastRWeb on the backend), tabplot and httr.
This is just a very small slice of the excellent talks I have attended. It was an awesome conference, thanks to the organizers, the speakers and to the participants. I’ll try to cover some more talks in a following Los Angeles R users group meetup, though the choice of topics will still be heavily biased by my main interests (and even within that subset I cannot really cover all the interesting talks). I encourage you to attend next year, so you can have it all.