Ubisoft has announced that Assassin's Creed II is compatible with the beta version of Uplay, its upcoming loyalty and rewards system.
The beta focuses on the Uplay Win aspect of the service, where you collect units (don't call them achievements!) for doing certain things in the game. These can then be traded for rewards, including exclusive in-game content.
Alternatively, you can save them up and use them cross-game to unlock things in future Ubisoft titles like Splinter Cell: Conviction.
What sort of stuff earns Uplay points then? Well, all the "actions" you can do for ACII overlap with the PS3's Trophy and Xbox 360's Achievement lists, including things like discovering particular assassin tombs, or reaching story milestones.
Rewards including things like downloadable PC/Mac wallpaper, an in-game knife belt upgrade for improved throwing knife capacity and a special Altair outfit.
Interestingly, there's also a "Uplay Exclusive Map", which offers access to the Auditore Family Crypt in Monteriggioni judging by the graphic.