I agree with E.J. Dionne--I think Edwards takes second in Iowa. My thinking is this: Clinton and Obama are engaged in a death-match there. Someone is going to win that death-match, and someone is going to lose it, and the person who loses it is going to be in big trouble. That's because the person who loses will not only have lost on semi-substantive grounds (by which I mean not just health-care or foreign policy but whether they have the experience, judgment, character, etc. to be president), but because they will have been diminished in the process. (The only thing worse than a nasty, ruthless pol is a nasty, ruthless loser.) Edwards, by contrast, seems to have toned down his rhetoric a bit, content to let the two titans fight it out. On top of that, given his support in the state in 2004, I think he starts with the highest floor of any of the three candidates.
It's probably a stretch to say that the plan all along was for Edwards to weaken Clinton to the point that she'd be drawn into a nasty fight with Obama, which would leave one of them mortally wounded, at which point Edwards could make his move. (Joe Trippi may be brilliant, but nobody's that brilliant.) But you have to give the Edwards team credit for leading the charge against Hillary and bringing her back to the rest of the field, which scrambled the race and left Edwards with an opening.
(Of course, if Edwards hadn't gone after Clinton, maybe Obama would have been forced to, which could have worked out even better for Edwards. But, then, Edwards was really, really effective, maybe more so than Obama would have been, and Edwards couldn't possibly count on that happening.)
P.S. Given the way things have gone the last week or two, it would be easy to interpret all this as an argument for why Obama will win Iowa and Clinton will finish third. That's certainly possible. But you can't for a second count Clinton out. If Hillary regains her footing, which she's more than capable of doing, it will almost certainly be at Obama's expense.
Update: Via Ben Smith, I see that Edwards has a new commercial up in Iowa, which completely jibes with Edwards's positive-closing-argument strategy:
It's still hard for me to believe this was the plan along (i.e., hit Hillary hard, thereby boosting Obama and drawing the two of them into a nasty fight, allowing Edwards to stay above the fray and cruise to a strong finish). Yes, as a reader points out, Trippi does spend a lot of time thinking and talking about the 2004 murder-suicide scenario involving Gephardt and Dean; on the other hand, my sense from talking to Trippi (see the lede to my profile of him) was that he thought Obama was fading by late summer, and that by challenging Hillary aggressively, Edwards would nudge Obama aside as the anti-Hillary.
That said, it does seem to be coming together pretty well now for Edwards. If he gets up for second or first in Iowa, I'm willing to give Trippi the benefit of the doubt.
Update II: Or, as another reader suggests, it could have nothing to do with Trippi...