ViewModel with MVC/Navigation in SL
"I've been writing about ViewModel (aka MVVM) pattern (here, here, here and more) and implementing it in Silverlight.FX for quite some time now, and it continues to be an exciting area for further thinking, and prototyping. This time around I want to cover how ViewModel and MVC fit together in an application at the same time." - [More]
http://www.nikhilk.net/Silverlight-ViewModel-MVC.aspx