Sadr is not only not the monolithic, unquestioned commander of the Mahdi "Army" militias, the more ambitious groups actually try to kill him periodically.

Sadr's game seems to be to let the IA and Coalition attrit the more radical militias, while decrying such actions to gain internal Shia political advantage. Like everyone in Iraq right now, he's hedging his bets between the military and political.

The most interesting aspect to this so far is the relative competence of the IA. They seem have to 5:1 or 10:1 kill ratios in every engagement with Sadr's people, who are basically street gangs with AKs and RPGs. With the Kurdish militias remaining essentially passive, that makes the IA the pre-eminent native active military force in the country.

Remember, there were major civil wars every decade of Saddam's rule. He was just the biggest, baddest, best-funded gangster in a country full of them. The violence may get a lot worse before they’re all dealt with. Ultimately, though, that task will fall to Iraqis.

I acutally think taking out al Sadr would probably cause more violence due to the fact that even though he may not control his "Army" but that they still look up to him and his words. It seems that one of the major problems of Iraq is that the people causing all of the ruckus have no fear. Societies are based on creating enogh fear in the people to keep them from doing whatever they want whenever they want. Once that fear is created, then societies can begin to use the carrot to pursuade people.
And in the same sense of South Park, How does one create fear in one who has none?