This is the third game created by Ryan Dewsbury on the Google Web Toolkit (he also wrote a book on the subject). His first effort was a Texas Holdem poker game called gpokr. He then created kdice, a Risk-like online game which was nominated for a Crunchies award last January.
XSketch is addictive and fun – I spent a lot more time testing it this morning than I really needed to for this post. Users can chat with each other during the game, give hints, etc. The tool to draw pictures is hard to use with a mouse or trackpad, leading to some very funny drawings.
You can also add XSketch to Facebook.