I have had two of my ISVs ask me pretty much the same question - what tools exist to help test rich client .NET applications - and did Microsoft have anything to help?
Well, firstly I don't think we do. Visual Studio Team System includes testing tools for unit testing of classes and performance testing of web applications but nothing specifically for Rich Client in the same way as IBM Rational Robot. However recently I became aware of these two tools - but as yet, have no experience of using the. If you have/do - please share here.