Silverlight MVVM and Testing

During my investigations into this crazy land I have found a few good articles (and many not so good…):

http://www.cauldwell.net/patrick/blog/MVVMAndTestingSilverlight.aspx

http://silverlight.net/blogs/justinangel/archive/2009/02/25/silverlight-unit-testing-rhinomocks-unity-and-resharper.aspx

Both use MVVM and both use RhinoMocks, but in subtly different ways.