Here are more Windows Phone 7 examples from Sigurd Snorteland. This time he’s taken open source Silverlight games and converted them to Windows Phone 7. The first is chess (called WP7chess) which lets you play against the phone, against another person or phone against phone (presumably using the turn-by-turn API MS has provided).
The second app is a Breakout style game called WP7Shock. It’s described as “A full screen Breakout-like game, with some enhancements: more than 10 bonuses, 11 brick types, teleports, explosives, customizable background sounds and secret level codes, tracks high score and related info using WCF.”
And here’s a video of wp7chess in action:
The source code is available from his site.