I was talking with some folks from Microsoft Technical Computing Group last week, and they turned me on to Microsoft CHESS. Extremely cool.
Their description:
CHESS is a tool for finding and reproducing Heisenbugs in concurrent programs. CHESS repeatedly runs a concurrent test ensuring that every run takes a different interleaving. If an interleaving results in an error, CHESS can reproduce the interleaving for improved debugging. CHESS is available for both managed and native programs.
http://research.microsoft.com/en-us/projects/chess/
http://msdn.microsoft.com/en-us/devlabs/cc950526.aspx
