U-Play(Ubisofts registration and reward program) is a feature within AC2, RUSE, and Splinter Cell Conviction, and more to come.  So far I've only used it for Splinter Cell and it seems like a straight forward system that rewards players for accomplishing certain tasks.  I strongly recommend that people sign up for it if you intend to play conviction because 2 of the 4 rewards are really worthwhile.  The first is the SCAR H which is basically the best rifle in the game even though it isn't suppressed.  The second is an entire game play mode titled Infiltration.  The other two rewards are a shitty theme and also an additional uniform for multiplayer which isn't too impressive either.  I hope that if they add more U-Play content for SCC, that they also add more actions to earn points towards them other than buying other U-play games just to make up the difference.