Charlie Cook, a most capable and balanced analyst, explains why it might be reasonable to think it is. Obama has all the advantages when it comes to organization, enthusiasm, money, and early voting. Any "Bradley effect" (and they’ll probably be very little) will be negated by the huge African-American turnout. The focus won’t shift from the economy prior to the election. Today’s polls are slightly worse for McCain than yesterday, and Obama’s is still viewed every favorably. Surges require more troops and a new strategy, and McCain doesn’t have either. I’m not SURE about the bottom line here, but Charlie makes it tough to ignore so much evidence.
So as not to seem too defeatist, let me add some Zogby data showing McCain remaining competitive and even gaining ground in the key battlground states, despite slide a bit nationwide. We still have to wonder whether McCain has the resources to close the deal in these states.
UPDATE: Zogby, sadly enough, shows rapid movement to Obama over the last 48 hours.