Bill Reiss has published a new version of SilverSprite for Silverlight 3.
The last time I started creating a sample game on this blog, I had to go through creating a game loop, handling keyboard input, dealing with vector mathematics, and a few other low level tasks. Along the way I created a helpers library which people could use to get started with their own games. A good amount of code from these samples made its way into SilverSprite, a free open source library that I created to make it easier to get XNA 2D games running in Silverlight.