For anyone who is using RStudio, there are some new features to note in the next release (0.95).
1 - Multiple projects, multiple RStudio instances
If you are like me and often have large things running, and want to work on something else, then it is nice to be able to have multiple instances (copies if you will) of the editor and programming environment running. I often find myself working on multiple projects, and I don't like shutting down and coming back to something when all I really need is 10 minutes to work on the other thing. So I was very happy to see that you can now fire up multiple copies of RStudio. You can even tie particular instances of RStudio to a particular project, with its associated files, and history.
2 - Integrated version control
I admit, I don't use version control nearly as much as I should, I still tend to depend on keeping old bits of code in files and then running the pieces that I need. But version control has gotten a lot easier with integrated versioning in RStudio using Git or SVN. I had been using Mercurial, but due to the built in integration with Git, am switching over (not hard, I only had like one directory that was actually using vc). What is really sweet about it, is that you can just create a project based on a current directory, and say you want to use VC, and it will initialize it and restart RStudio, and you are good to go.
One reason I will be using Git over SVN is the ability to stick with local repositories, whereas SVN would require a whole server set up on my machine or somewhere else. And it seems pretty easy to use.
As of 1500 EST on 20/01/12, the download page still showed the old version, but the documentation for version control is up. If you want to get the version with projects and version control as a preview release here http://www.rstudio.org/download/preview.
Edit: The new version is available on the main download page.