After a few annualized spin-off sequels, it's fair to ask what will set Assassin's Creed 3 apart to reinvigorate the franchise. "Sure," you say, "it has a new setting and hero and animations and a graphical upgrade and tree traversal, but what else?" Well, Mr. Hard-to-Please, how about online co-op?
IGN spotted mention of online co-op for 2-4 players in the game's official description in the Xbox Live Marketplace. That descriptor has since been pulled, which could indicate it was a mistake. Of course, it could also mean that Ubisoft asked Microsoft to stop spilling those particular beans. The listing still mentions online multiplayer for up to eight players, confirming the return of Assassin's Creed competitive offerings in some shape.
If the game does feature a co-op mode, it would probably have to be in a separate mode with various assassins, or to have the second player select a different assassin. Having two Connors running around wouldn't make a whole lot of sense.
Shacknews has contacted Ubisoft regarding the potential mode, and will update as more information becomes available.