Like other people on that Obama conference call today, I noticed campaign manager David Plouffe spending an awful lot of time talking about why a vote for John Edwards is essentially a wasted vote, since (Plouffe claimed) he doesn't really have the resources or the organization to compete after Iowa. It's possible that the Obama people see Edwards as the candidate with momentum in the home stretch. Or it's possible that Obama and Edwards are just competing for the same bloc of voters--pro-reform, skeptical of Hillary. (Or both.) Tough to say, really.
Also, Ambinder says some reporters are speculating that the call was intended to pre-empt what will be lousy numbers for Obama in tonight's Des Moines Register poll. For what it's worth, I did get the sense Plouffe was basically saying: Don't read too much into the polls. We have the best organization, which is going to be the difference here.
Relatedly, Plouffe said at one point, "We've consistently led ... among those definitely attending [the caucuses] in our internal research… We're focused on how we're doing among those deadset on going to that caucus room Thursday night." In my contemporaneous notes, I wrote, "Probably trailing among likely voters"--which, obviously, is what polls report.
That said, don't reflexively discount the importance of what Plouffe's saying here. Having a lead among definite attendees is not nothing (though it does somewhat muddle the CW about a big turnout being good for Obama.)