The video of Joe Biden calling on Missouri state senator Chuck Graham to stand up, before realising that Graham is a paraplegic and confined to a wheelchair is certainly doing the blog rounds (it's here on youtube).
It's embarrassing of course, although I think Biden recovers from an awful gaffe pretty well, but that may be because he does make rather a lot of them. It's the same Biden, after all, who plagiarised almost word for word a Neil Kinnock speech many years ago. More seriously for the Democrats than their vice-presidential nominee's mishap, is their presidential nominee's level-pegging with McCain.
Obama has been on the defensive since his own convention, when despite a hugely popular final speech, he and his party failed to land a blow on McCain. And that was before McCain unleashed Sarah Palin. There are real concerns in the Democrat camp that this election is slipping away from them yet again - an extraordinary state of affairs given the dismal popularity of Republican incumbent president George W. Bush, and the dire state of the American economy. Today's memorials for the victims of 9/11 may provide an opportunity to review the unpopular outcome of Bush's subsequent wars (consensus has it that Iraq looks hopeful, though far from won, while Afghanistan remains a nightmare). Whether that provides an opportunity for Obama to rediscover his political voice (he did, after all, vote against the Iraq war) and start regaining the political initiative remains to be seen, but recent history is littered with the political corpses of Democratic presidential candidates who failed to deliver the killer punch to their weak opponents (Dukakis against Bush Snr., Gore against Bush Jnr., Kerry likewise), and it would, alas, be entirely in character if Obama joined them.