I just read this really well written and interesting document by Nikola Mihaylov.
"Nikola Mihaylov is a Software Design Engineer in Test at Microsoft, working on the WPF/Silverlight tools for Visual Studio. Nikola’s first Silverlight game topped the http://silverlight.net charts for 2 weeks after its v1.00 release in 2008."
It gives you a great idea of how to build a Silverlight game, and for the people who have already build games on their own, it's still good reading. I mean, we all want to learn something new all the time, right?
The document can be found on Nikola's blogpost here: http://blogs.msdn.com/nikola/archive/2009/02/05/anatomy-of-a-silverlight-game-avoid-common-mistakes-when-building-silverlight-online-games.aspx?CommentPosted=true#commentmessage