Ibrahim al-Jaafari won the Sadrist movement's referendum on the next prime minister, with 24 percent of the roughly 1.5 million ballots cast.
Jaafar al-Sadr, the son of Dawa party founder Mohammad Baqir al-Sadr, placed second with 23 percent of the vote; Qusay as-Suhail, a Sadrist MP (and rumored candidate for the PM job), placed third with 17 percent.
Nouri al-Maliki was fourth, with 10 percent, and Iyad Allawi placed fifth with 9 percent (full results in English are here).
The referendum has no binding legal authority; the Sadrist leadership says it's merely a way to gauge public opinion. Jaafari is trying to position himself as something of a compromise candidate, a third party who wasn't involved in the pre-election fighting between Allawi and Maliki; the referendum gives him a boost.
The results of the referendum are clearly a roadblock to an alliance between Maliki's State of Law movement and the Sadrists (and, by extension, the Iraqi National Alliance). Maliki and Jaafari have an unpleasant history, and tensions remain despite recent efforts to bury the hatchet. Maliki won't be happy if the Sadrists condition their support on Jaafari's installation as prime minister.
Reidar Visser notes that Jaafari might also be unacceptable to the Kurdish parties:
Back in 2006 he was the PM nominee that was "unacceptable" to the Kurds, which led to his replacement by Maliki (who in turn ended up being seen as equally "unacceptable" by many Kurds).
Jaafari held a meeting yesterday with representatives from the Iraqiyya coalition; he issued a statement afterwards endorsing a government "formed without excluding any political component."