This is apparently going to be included in the Avengers Blu-Ray/DVD combo pack they're putting out in September (and I will be be picking up as soon as possible). Apparently some civilians find one of the Chitauri's weapons and wreak havoc with it until some SHIELD agents come to stop them. If you're a true geek, the Hot Toys Avengers line (which I really need to post soon) comes with one of these weapons.
Brett Kelly. I gotta figure out what he can draw for me!!