Dead Space 2 will be getting a multiplayer mode in which players will control either Necromorphs or "soldiers" (presumably not welders, then?). GamerNode claims that the mode will consist of "deathmatch-style combat" and will be just one of several multiplayer game modes included when the game launches in early 2011.
Additionally, the source claims that pre-orders of the game at any outlet would net purchasers a free download of Dead Space: Ignition. If you pre-order it at GameStop, you'll allegedly get another bonus: a rivet gun.
Update: EA could only confirm the inclusion of multiplayer in Dead Space 2 to Joystiq, saying, "Dead Space 2 will feature multiplayer where you'll be able to strategically dismember your friends for the first time." Hopefully we'll hear more soon.