Burton has finally been officially announced. The Visual Studio 2005 Team System is basically everything that VSS wasn't.
- Integrated Unit Testing
- Code Coverage Tools
- Enforced Check-In Policies (e.g. you must pass a unit test before the code can be checked in)
If you are a developer (as opposed to a straight coder), these changes are quite exciting. I know I was impressed when I first saw them. Look for more information at the AskBurton blog.