Claire McCaskill is going to go all-out for Obama in MO. If he wins there, she (and others) will view herself as Presidential Timber.
Obama has already shown himself capable of a strong showing in Virginia. He will have the assistance of Tim Kaine, Mark Warner, and Jim Webb. John Warner will not be out on the stump for McCain. George Allen might but that is worthless.
If people can wrap their heads around Obama not being an Evil Muslim or planning to enslave the white race or eradicate the Jews, places like Florida and Ohio are up for grabs. Ohio, as per usual, will almost certainly vote against its best interests, though.
States that could be impacted by VP choices- New Mexico (Richardson), Kansas (Sebelius), Georgia (Nunn), and Indiana (that fucking twit). McCain has to be considering Romeny to help put him over the top in Michigan.