This used to be a part of IronPython and is now a separate project. They now support different interpreters like CPython instead of IronPython only. Together with AnkhSVN and Mono Tools this makes Visual Studio 2010 a pretty nice place to work in to be honest.
I think Microsoft is moving in the right direction with these kind of extensions. Please make more! (Preliminary Wish List: Bash/Ksh/Posix Shell script extension, Ruby extension, Dalvik/Android extension)