bf2 has a thing called deviation modifier depending on how long you've shot, if you are moving, crouch etc. The modifier makes the bullet deviate with a random direction, and this modifier changes depending on situation as I said.
For instance if you shoot single shots you'll hit pretty much excactly where you aim, but if you shoot a whole mag in a single cascade, you'll get a lot of devation and not hit much after the first few shots.
We've got complete controll over these modifiers for our own weapons obviosly, not sure how we'll do it though. Having them makes it all more realistic, you'll not hit very good while you're running for example, but hit much better when you stand still and crouch.
we'll see 
"i rar you with high compression alogrythems" - teh hobbit