So if you haven't seen Thor, this post should be ignored.
SPOILERS AHEAD!
So, how do you think the Cosmic Cube fits into the Avengers? I was talking to Harry over FB chat and I kinda made a rough outline of what may happen on the Avengers. The Cosmic Cube will appear on Captain America, I'm guessing that's what's giving Red Skull his power. So, for the Avengers, Hulk is currently under arrest by SHIELD. Jane Foster finishes her theory on wormhole, makes one, and connects it to Asgard, that's how Thor comes back to Earth. Under Loki's influence (as shown in the post-credit scene of Thor), Selvig begins studying the Cosmic Cube and somehow taps into its power, when this happens Loki steals the cube and begins destroying Earth. Iron Man, Captain America and Thor all face off against him, individually, and get stomped. They band together and get stomped again, so what do they do? They bring in Hulk as a necessary evil and finally beat Loki, and in some kind of scene, the audience finds out that Loki was working with Thanos (Avengers 2 set!).... roll credits.