Microsoft has announced plans to release the source code for the .Net framework (comments and all!). This is awesome news for those of us that stress the framework fairly regularly.
Of course, Reflector gave us the ability to view the code already, but now you will be able to view the source code comments as well as step into the code with VS 2008. In fact, with VS 2008, if you don't already have the source code and you attempt to step into it, it will prompt you to download it automatically.
It's not quite open source, but it's still a big step for Microsoft. VS 2008 is certainly looking like it will be an interesting release! Hopefully it will be ready by the end of the year (please don't make me wait too long!:).