Has anyone been using a .NET mocking framework that they have found compatible with Monotouch? I am curious about compatibility with NMock, NSubstitute, Moq and other frameworks before I attempt to use one.

Xamarin just beefed up its unit testing support, but no mention of a mock framework. FYI, I am hoping to do a lot of my development on VS 2010 for the non-UI bits and move to the iOS platform when the UI comes into play.

Thanks for the help.