I disagree with many of his sub-points, but Russ Smith touches on an emerging storyline: the certain combination of acute anger, despair and bitterness on the left if McCain's late comeback snatches victory away from Obama in the homestretch of this incredibly long and intense campaign. The response to Kerry's defeat was muted by the fact that few liberals were especially smitten with him to begin with. But the fallout this time could be pretty raw stuff. And that doesn't even factor in the guaranteed, sure-to-be-vicious debate about whether the Clintons are to blame or were the only way to avoid such an outcome.
On a semi-related point: The smart early-summer CW on this race was that it would likely be a wide margin one way or another: Obama would either blow up or melt down, winning big or losing badly. Now it looks like we're headed for another nail-biter. My best guess is that, much like 2004, when the ephemeral response to a bin Laden tape the Friday before the election seemed to make a decisive difference (at least a lot of Kerry aides thought it did), the race will stay very close and random last-minute news events will likely tip the balance.