I've been playing with the unit testing in Visual Studio Team System (documented here), and it's awesome! The parts I love the most are:
- Integration of the unit testing framework with Visual Studio
- The ability to select some code and have it generate the skeleton of your unit tests
- The integrated code coverage. I love that you can run a test and then see which lines were hit and which weren't right in the code editor!
There's been a lot of feedback to include the unit testing in the basic version of Visual Studio.