I am working on a data warehouse administration portal using Silverlight with the MVVM pattern. It was hard to find an end to end example with associated sample code. However, I found the following two articles, when mashed, provide a good overview. I used the first article by John Papa to build the data service using WCF. I used the second article by Shawn Wildermuth to design the front end.
John Papa: http://msdn.microsoft.com/en-us/magazine/cc700340.aspx (this article has since been removed – vp)
Shawn Wildermuth: http://msdn.microsoft.com/en-us/magazine/dd458800.aspx