As of today AC brotherhood's online component hasn't had too much in the way of teamwork based game modes. That has apparently changed with the new free DLC pack dubbed, "The Animus 2.0" pack. It brings you a brand new map and a brand new attack and defend mode where one team attempts to steal chests full of treasure and the defending team of course tries to stop the opposition! So far from what I've played it is a great addition to ACB and in the next Assassin's game coming in late 2011 there needs to be more team based stuff