We have a great present to all the Windows Phone developers! A Windows 7 Super Sample!
This is a complex sample using the modules Location and Users. The sample shows you how to create a new user, verify his mail and log in. By using the Map engine and services you can see other users on the map, their statuses and can open their info pages with private chat. You can use chat to talk too all registered users on the friend’s page.
This sample covers many usual things about communication and geolocation. And is available to download on the Windows Marketplace for free!