Oh, I wouldn't put too much trust in Sadr since there is much evidence that suggests that he acts much more in the interests of Iran than Iraq. And, even though there are currently activities initiated by Sadr that might convince some that he acts in the interest of Iraq, this is likely to be an illusion long-term.

In short, I think the Iranian regime is begining to realize that, as long as there is turmoil in Iraq, the American forces (and influence) will be sizeable in Iraq. So, the quicker that turmoil significantly decreases, the sooner the American forces leave Iraq in bulk, and the sooner the Iranian regime can turn Iraq into somewhat of a province of Iran. Or, at least another Lebanon or Syria.

(If you ask me, the guy to watch in Iraq is Sistani rather than Sadr. He has enormous religious sway in Iraq and he wishes that Iraq has a secular government that exists outside the influence of foriegn entities.)

And, believe it or not, not all of the Ayatollahs in Iran actually hate the US. It's just unfortunate that they aren't the ones with significant political power in Iran right now.