It took 4 different greens screen setups, a good amount of animators and layerers, and about seven jaillion billion hours of mind numbing labor to amount to several seconds of awesome footage. The final battle at the end of The Avengers had to have been the best scene of the film (not including HARRY DEAN MOTHERF**KING STANTON'S scene of course) since it basically makes up for years and years of advertising.
Industrial Light and Magic uploaded this video to YouTube in which they explain how they put some of this stuff together. I have to admit I was losing my mind watching all of it the first time, so I failed to notice how good it all looked. I guess now that's been a couple of months, it seems like a good time to appreciate all of their hard work.