It seems to have stopped, as the New York Times' expert Nate Silver notes. Indeed, the President's numbers are ticking upward slightly.
So, what should we make of shape-shifter plutocrat Willard "I'll Say Anything" Romney claiming that he has "momentum?" As VP Joe would say, "malarky." It's a common tactic to try to juice the undecided voters into thinking your candidate is inevitable, so go with the winner. It's going to be a close race, no question, and Willard's bravado is like so much of his campaign: he'll say anything to get elected.
BONUS: Sam Wang at Princeton Election Consortium agrees with Nate (and takes apart David "Bobo" Brooks in the process).