So Muqtada al-Sadr told his followers to back off. I'd read somewhere that he's a better politician than anything, and I think this shows it. Now he can claim that no one loyal to him is involved in any further fighting, and lay the blame for any deaths and damage on the Iraqi government while preserving his persecuted-by-the-Americans-and-their-puppet image for the elections. He can also let Maliki clean out the rebel elements in his organization, since they'll pesumably be the ones still fighting.
This also calls out Maliki in another way; it removes what everyone believes, despite his statements, was his prime target. It also could make Maliki look really ineffective if the fighting continues and he can't get things under control.