The Weekly Standard's Matt Continetti and I did a bloggingheads debate last night in which we chewed over the politics of the Petraeus testimony, along with various morsels from the presidential campaign.
In brief, I agree with Mike and Eve that Obama sounded impressive while questioning Petraeus. But I think the Democrats (this goes for Hillary, too) face a real dilemma on Iraq that's every bit as thorny as John McCain's.
McCain's problem is obvious: The war has become spectacularly unpopular. On the other hand, he has the virtue of having a pretty coherent position: We've made progress; let's stick around and continue that progress.
Obama and Clinton have the converse problem: Politically, their Iraq position is a real advantage. But the position is substantively incoherent: They want to withdraw most of our troops from Iraq relatively soon and, as Obama suggested, leave behind the kind of messy but semi-functional status quo we have now. But that semi-functional status quo would almost certainly not persist if we withdrew most of our troops. (See, for example, Basra.)
Now, I'm not saying this is the wrong position. It may be that the opportunity cost of keeping our troops in Iraq--both in terms of dealing with other strategic threats, and the sheer financial burden--doesn't justify sticking it out in Iraq given the slim chances of eventual success. (In fact, I think that's actually how I feel.) But, in that case, what you favor is leaving Iraq in really bad shape because we've got other things to do. The option of withdrawing soon-ish and more or less preserving the current status quo doesn't really exist as far as I can tell.