I did an interview for DZone at DevTeach Toronto a few weeks ago and that is now available online here.
In the interview I described what the ViewModel pattern is all about and how it manifests itself in Silverlight and WPF apps. I also talked about what I found most interesting in Silverlight 4, specifically the enhancements in data binding and commanding that close the gap a lot between WPF and Silverlight and provide the glue that is needed to really do MVVM well.
I also talked about Prism and what it provides for you: Commands, loosely couple events, UI Composition, and Modularity.
There is also a very short (~1 minute) demo that shows some of the characteristics of the code of an MVVM implementation.
Hope you enjoy it.