From an AP article on FR now:
Iraq's prime minister has told Shiite militiamen to surrender their arms or face an all-out assault by U.S.-backed Iraqi forces, senior Iraqi officials said Wednesday, as President Bush said he will commit an additional 21,500 American combat troops to the war. Under pressure from the U.S., Prime Minister Nouri al-Maliki has agreed to crack down on fighters controlled by his most powerful political ally, Muqtada al-Sadr, a radical Shiite cleric, according to officials. Previously, al-Maliki had resisted the move. "Prime Minister al-Maliki has told everyone that there will be no escape from attack," said a senior Shiite legislator.
I am going to make a prediction on that - Sadr is going to announce his militia will "cease hostilities". this will likely have been pre-arranged through Maliki, but that doesn't matter.
it makes little sense for Sadr to engage, as US and iraqi forces are taking down the Sunnis.