Nikolai Tillman and Peli de Halleux announced the first public release of Pex (under Microsoft Research license). From the website:

Pex (Program EXploration) is an intelligent assistant to the programmer. From a parameterized unit test, it automatically produces a traditional unit test suite with high code coverage. In addition, it suggests to the programmer how to fix the bugs. Watch the screencast!

Pex generates Unit Tests from hand-written Parameterized Unit Tests through Automated Exploratory Testing based on Dynamic Symbolic Execution.

PEX
See the full-size image at the Pex Website

You can download Pex here. It's recommended to have Visual Studio 2008 Professional to try out Pex.

As you might remember, Peli de Halleux is a Belgian guy that moved to Redmond in October 2004 to work for Microsoft . Before that he developed the first versions of the MbUnit unit testing framework as a hobby project. And of course he was also known for the different Reflector add-ins that he built.