Because of the quick decline of the Obama/Biden ticket, I can envision the possibility of dropping Biden from the ticket, or, rather, Joe Biden dropping off of the ticket.
Not Beyond Possibility
Senator Biden has had a history of serious health problems with brain aneurysms and may 'suffer' a similar type of condition so to be released from the race. This will do three things for Obama.
1) Sympathy vote
2) Combat the Palin phenomenon by allowing the selection of Hillary Clinton as the new running mate without losing face.
3) Subtly warn the electorate of the dangers of John McCain's old age and frailty. Biden is about six years younger than McCain.
Get your Biden digs in now, 'cause we may not have him to kick around much longer.
Perhaps that's the 'change' that Obama has been preaching about.