That's Krugman's suggestion. This suggestion puzzles me for a number of reasons. Krugman posits that Hillary's inclusion in the ticket will help Obama recapture jilted Hillary supporters and lower/lower-middle income white voters who Hillary has typically won over. On the former, I don't really think there are that many jilted Hillary supporters. I am guessing her conduct at this point has taken care of that. The few remaining people whose noses are bent out of shape over Hillary's failure to secure the nomination are those who had been promised a gig in a Clinton Administration (which makes me wonder if Krugman had been offered some position, say CEA chair, as he has been in the tank hardcore for Hillary on his blog and op-ed pages).
The real question is whether or not Hillary will be able to bring her blue collar white supporters. I doubt it. I think many of those who are supporting Hillary are not so much supporting Hillary but opposing a Black male. I think for many of those voters a Barack-Hillary ticket would be a diversity freak show. For Obama to appeal to these voters he will need a white male, plain and simple. Ideally this potential VIP would also bring other credentials than his whiteness (this rules out John Edwards), such as foreign policy experience or experience in general.
But the other reason Hillary would be an awful choice is that she more anything the Republicans can do themselves, will engergize the conservative base.