Matt Duss passes along news that the Sadrist trend is tightening the rope that binds Sistani to the Maliki government, in all its sagging popularity and misdeed:

An aide to Muqtada al-Sadr has lashed out at Grand Ayatollah Ali al-Sistani, Iraq's most revered Shia cleric, for keeping silent over clashes that have killed hundreds in Baghdad. [...]

Speaking at Friday prayers, Sheikh Sattar Battat, an aide to al-Sadr, said he was "surprised" that al-Sistani had failed to condemn the violence.

We are surprised by the silence in Najaf where the highest Shiite religious authority is based," he said, referring to al-Sistani.

"For 50 days Sadr City is being bombed ... Children, women and old people are being killed by all kinds of US weapons, and Najaf remains silent."

Battat said the al-Sadr movement has not seen any "reaction or fatwa [religious decree] from Najaf" criticising the government assault on Shia fighters in Sadr City.

"For us this means that Najaf accepts the massacre in Sadr City," he said.

As Duss observes, Sistani's acquiescence will likely play to Sadr's advantage:

One of the central elements of the elder Sadr’s program (and now of Muqtada’s) was a distinction between the “silent clerics” (represented by Sistani and the Najaf establishment) — bookish sorts who stay remote from the lives of their people — and the “speaking clerics” who take part in the suffering and struggle of the Shia, as Sadeq did. And here the “silent clerics” once again stayed silent while Shia were crushed in Sadr City, of all places, while medical care, food, and shelter are being doled out in Muqtada’s name. It doesn’t require any math to see that Sadr benefits politically from this.

Not just politically, but religiously as well - to the extent the two are separate.  Such a strengthening of Sadr vis-a-vis Sistani is, in my opinion, a shame for reasons beyond the silent/speaking distinctions set forth above (though, obviously, I am not an Iraqi and thus should not get a vote).  Babak Rahimi has an excellent summary of some of Sistani's religious views, and how he espouses a brand of theology that can co-exist with liberal democratic traditions (at least, moreso than Sadr's):

Like his father, Sistani is an adherent of a democratic Shi'i tradition that dates back to the Persian Constitutional Revolution of 1906 to 1911 and continued with the Khatami reformist movement (1997–2005). [...]

Sistani’s insistence on recognizing Islam as a fundamental component of the Iraqi constitution is not intended to make Iraq an Islamist state based on juridical sharia strictures, but rather to limit the total secularization of the constitution, which would deprive a Muslim country of an “authentic” national identity based on its Islamic heritage.

Sadr, on the other hand, is much more amenable to vilayet-e faqih, or an Iranian style rule by clerical jurisprudence that pays less regard to individual rights.  However, our continued assault on the Sadrist trend has been backfiring and increasing his popularity at the expense of religious leaders like Sistani that we should be acting to empower. Shockingly enough, military actions in densely populated areas leading to massive civilian casualties aren't very well received in the target population. 

Sadly, the strategic thinkers in the Bush administration seem incapable of devising a plan to empower favored factions that doesn't involve the employ of self-defeating brute strength.  It would be better if, instead, we adopted some of that fancy counterinsurgency doctrine that Petraeus is supposedly implementing.