<<And no,AQ is blowing up Shiites because it is in their interests to do so.>>
They're not the only ones whose interests are served by AQ blowing up Shi'ites or vice versa.
<< A civil war creates a vacuum. They want to fill that vacuum without doing the heavy lifting. >>
Seems to me that the civil war also creates the excuse for the U.S. to stay on without Bush & Cheney having to admit it's all for the oil. Extends their window of opportunity a few more months at least, years at most, before the public gets really fed up and won't tolerate any more. How convenient for them, eh? What a lucky break! Imagine, just when they need civil war, a civil war just happens to spring into being. Ever wonder how that happens?