Read the original post by Jason Jarrett at Developing on Staxmande
In short, it allows you to run your Silverlight tests on a Continuous Integration server or alongside your daily development.
Fore more information go check out the project site http://statlight.codeplex.com
Some ramblings (about the project).
It’s funny how the release cycle of this open source project has turned out. I don’t have any sort of calendar reminder that pops up saying “it’s been 4 or 5 months and time to get out a new release”. However, since I first open sourced the project I’ve put out a new release on a pretty consistent 4/5 month cycle and have done so since December 2009. It just so happens about every 4/5 months there is enough features and or fixes piled on top that It’s time to put out an “official” build. Not bad for a part time (free to the community) gig.