As I am totally awaiting this game, I have followed every little bit of info I can gather. I just read an interview with Cevat Yerli (executive producer of Crysis) and it seems as though it will take advantage of mutliple cores.
Maximum PC: How many execution cores will the game support? what will you use the different cores for?
Yerli: Our multicore implementations encompass physics, AI, game logic, and particles and are balanced over two or four cores to take next generational advantage. Of course, we also run on single-core highly optimized.
Yerli : "So you are best equipped with quad core (if you have the budget). But Crysis will do great on dual-core configurations as well."