A little thing, but at best a gaffe, and at worst a tacit admission:
How Ben Porritt of the McCain campaign put it:
"Barack Obama sounded as though he turned over the top spot on the ticket today to his new mentor, when he introduced Joe Biden as the next president. The reality is that nothing has changed since Joe Biden first made his assessment that Barack Obama is not ready to lead. He wasn’t ready then and he isn’t ready now."
"Joe's the one who's supposed to trip over his own tongue for our amusement, Barry. Although if you picked him to balance out the ticket in that regard, trust me: it was redundant."
Oh, the fun that we will have with this pick for the next two months. See also The Other McCain for the inevitable Terry Eagleton comparison. Who? Trust me, kids: you'll find out.