This may or may not be the conventional wisdom, but I figured I should just say a few words about what's likely to happen in the coming weeks, and why a lot of us think it favors Obama (for reasons above and beyond the ones I mention here). The next round of contests, slated for Saturday, includes Lousiana, Washington state, Nebraska, and the Virgin Islands. Lousiana is going to be nearly 50 percent African American, Nebraska and Washington are caucuses, which Obama dominated tonight, and the Virgin Islands are the Virgin Islands. (Though, if I must, I think people give Obama the advantage there for demographic reasons, too.) The next day is Maine, also a caucus, and then one week from last night is Virginia, Maryland, DC--all expectated to favor Obama demographically. The Tuesday after that brings Hawaii--Obama's native state--and Wisconsin, which should also be friendly territory for Obama.
And then we wait two weeks and throw-down in Texas and Ohio, at which point a lot of people think this competition could end. (Rhode Island and Vermont also go that day.) Between the Latinos in Texas and Hillary's establishment support in Ohio, those will almost certainly be her firewall states. On the other hand, Obama is going to have two weeks to focus on those two states alone. Between his near-certain money advantage, the momentum he'll pick up from the intervening contests, and the fact that he tends to do pretty well in states where he has time to campaign, I think you have to give him the overall edge going forward.
Update: For what it's worth, I don't think Obama will end things on March 4. If I had to guess, I'd say he wins Ohio and Hillary wins Texas, but that the Texas loss isn't big enough to disrupt his momentum...