Actually... As emotionally satisfying this might be if true, it could be very bad. We have, mostly, neutralized al Sadr; whether we bought him, or scared him, or other Iraqi leaders have restrained him, he's mostly just been a blowhard lately.
If he has been taken out, who knows what could come next.
And if he recovers... well he's going to have a Messiah glow that could almost rival Barack Obama's.