Every rumour we've seen concerning Dead Space 3 seems to imply that Visceral will be shaking things up quite a bit in the next iteration of their Dead Space series. Whether they're going first person, taking advantage of the Frostbite 2 engine or setting everything on a harsh, snowy planet, the develeopers want Dead Space 3 to be an entirely different experience.
So add this one to the list: IGN say that Dead Space 3 will feature co-op multiplayer. The story will mirror that of the single player, but adjustments will be made for the second character. The example given is that in the single player, Issac will fight his way out from under rubble by himself, but the same cutscene in co-op will show both Issac and friend managing to escape.
They also say that certain events won't happen unless Issac is on his own, so it'll probably be worth finishing the game on single player if this turns out to be true. Here's hoping it's local co-op and I won't have to find strangers uninterested in exploring, fighting or fairness to play this one with me.