The problem with TypeMock right now is that it is not known. If one searches for unit testing for .NET, he'll find NUnit, MbUnit, NMock, DotNetMock, and some small reference to csUnit. I'm surprised that I found TypeMock. I don't even remember what obscure blog post got me here. I suggest that put an article on codeproject.com and mention it on in comments for articles about unit testing in .NET. You will have more requests for Mono once more people know about it. Assuming that you did not use a lot of P/Invoke, the only problem would be the environment variables.