It looks like the research project Spec# that Microsoft has been working is available to download and play with. Obviously I am behind on the times as this stuff looks like it has been available for some time.

From what I understand from feedback form the ALT.NET event in Seattle and the channel 9 videos ( &, Spec# aims to provide us with compile time verification of what constitutes a method or class contract. Just as the shift from VB to .NET meant I had access to a strongly typed world, the shift Spec# looks to offer is further verification on a class or method contract. At a basic level this gives verification on null parameters and some contractual awareness of exceptions.

I doubt there is any production value in what spec# provides at the moment, but is worth keeping an eye on as the expectation of reliable and durable software keeps increasing.