in the E3 demo Randy Pitchford states that there are 4 postures in the game: stealth, patrol, relax, and combat posture. But he also says that the men change postures themselves based on the situation. I just hope that the player will be able to control the posture as well.

I think they are all automatic. We have seen that stealth and combat are automatic

I agree that it is probably auto. manual would be cool though, and would bring a whole new tactical element to the game. i guess we will have to wait and see.