So, I bought the Civil War trade recently, and Mark Millar might just be the best comics writer around right now. This book was really like a smack to the face, which is what Millar has done so well in the past, with books like the Ultimates.
For those who just failed their Knowledge (Popular Culture) skill check (DC 20), recently in the Marvel U, a tragedy caused by under-trained super heroes leads Congress to push for registration of all superhumans. They'll be trained by the government, licensed, and the government will know their identities (though average citizens won't). If they break the law, they could face civil and/or criminal penalties.
Basically they'll have the same rights, but also the same restrictions, as, say, an undercover FBI agent.
This move divides the superhuman community down the middle, with Iron Man leading the pro-registration side and Captain America leading the anti-reg side. There's villains on both sides too. Basically, this war overrides normal considerations of good and evil.
When I first heard the idea, I thought "dumb dumb dumb". Of course, I didn't think they'd actually go all the way with it either. For an example of a direction I didn't think they'd take, in the aftermath of Civil War, there are two Avengers teams, one sanctioned by the government, consisting of Yellowjacket, Wasp, Iron Man, Ms. Marvel etc and the other an underground team of anti-reg holdouts, consisting of (among others) Luke Cage, Spider-Man and Iron Fist.
In other words, the Marvel U is different than it used to be. They didn't wrap up the story with a Deus ex Machina in the last issue of the mini-series.
And oh yeah, if you want to see Spider-Man kick Mr. Fantastic in the throat, or Thor kill Goliath with a lightning bolt, then you should also buy this mini-series.