It would be a good national ticket, but it may also be a good Iowa strategy:

A source close to the Biden campaign described a possible arrangement, now under discussion between the two camps, that could apply to certain precincts where Biden can't meet the 15 percent viability threshold, but where he is backed by local officials with the clout to move Biden supporters to Obama. In return, Biden could capture some of Obama's overflow in precincts where the Illinois senator has more than enough support to win.