EA has posted a new dev diary for Dead Space that covers the concept of "strategic dismemberment" in
Dead Space. In the game head shots don't give you the instant kill you see in every other game out there, rather you have to figure how the right way to cripple an enemy so that you can finish them off in the quickest way possible. It's a fairly interesting concept that I think will take some getting used to as they're working against years of gamers being programmed to go for the head.