Spoke to a House Democrat who's been with Obama since the start. He made a good point: Does anyone really believe that John McCain will wind up with nearly half of Hillary's former supporters? Of course not. If you assume a lot of those people are coming home, and I do, then Obama can probably count on a few points of currently-invisible buffer.
This of course assumes there's no disastrous rift-renewing event this week or later in the campaign, which one can't entirely rule out. But I think it's fairly persuasive spin overall.
This Congressmen is also eager to see the Obama camp hit McCain harder on his record of legislative flip-flops, which come to think is really not a theme they've pushed hard so far.