I just posted a new tutorial that uses Visual Studio 2010, the Silverlight 4 RC, and WCF RIA Services RC. This tutorial walks through the creation of a Silverlight Client (a golf handicap application) that uses WCF RIA Services to maintain and update data stored on a server.
The application is sufficiently complex to show some real-life requirements while not being too complex to make it hard to comprehend.
This tutorial uses a traditional event-driven paradigm with code-behind to interact with the UI and the RIA services. I plan to refactor the code and create a second version of the application using the MVVM pattern and publish that tutorial in April.