They just got a new trailer up on Gametrailers from the Tokyo Game Show
Game looks so cool, can't wait till it comes out. Just hope my PSP lasts till then. They are saying that it's going to be one of those that will go along with the storyline, unlike MGS: Portable Ops (more of an side story). Peace Walker is after MGS3 but Before Metal Gear (not Metal Gear Solid).
And here are some previous trailers if you missed it.
How cool will it be for the 4 player Co-Op?
EDIT - NOO!!! I mispelled the topic title, can a mod change it to "MGS: Peace Walker"? Thank You.