There's definitely a coop mode. On the box, it says 2-8 players online and so far multiplayer has only been 4v4 (8).
Well, couldn't that just be costum game? 1-1 against a friend? Or would that not work in this type of game we have seen?
There are most likely one or two more modes because all this information isn't coming from the review disks. Last week Sony had many websites come check out the mp so sony may have only showed these two modes at the secret event and have more still unshown (speculation).