Crytek have detailed the new MP modes in the following trailer.
I played the PC MP demo last month and came away very impressed with the Hunter Mode, it was certainly a lot of fun.
The game on PC looks notably better now, there's no overall parity with the 360 as far as the visuals concerned. I tried to get some info on the specs from some of the Nvidia guys that were meandering around, but they told me not to expect them until sometime in late November - early December. I also asked what specs the PC demo build was running on, but again they wouldn't say. I also couldn't tell from sneaking a peak in the backroom and looking at the PC cases, but at least I nabbed a T-shirt while there :P