Valve have released a trailer showcasing what Portal 2's co-op gameplay will be like. It may be short, but it gets the point across, and really makes us excited for some of the more advanced co-op puzzles we'll see when the game launches this February. I can also see Portal 2's co-op mode being a lot of fun just to screw around with sandbox style with a friend - all we need is some quality ragdoll physics!