Simply Appalling has an excellent discussion of views on the Iraqi Civil War (previously known as Shrub's War). The post concludes with SA's advice:
I have seen no indication that Iraqis of any persuasion are inclined to glom onto the Americans. And if any of them were so inclined, it is more likely than not that the Americans would be pushing them away, since they prudently avoid a close association with Iraqi forces. It is perfectly ludicrous to suggest that the U.S. military is going to be much in the way of glue.
There is speculation that the Iraqi civil war will bring in other participants—Turkey, Iran and the Sunni Arab countries. Perhaps the American role will be to fend off invasion by these other interested parties while the Iraqis have at it.
But the wisest, most humane course would be to announce a timetable for American withdrawal "in an orderly, but rapid manner" and "without delay," as Congressman Steve Rothmann is now urging. This would leave the Iraqis so stunned, at least temporarily, that they might be able to find some unity at the prospect of an American withdrawal.