No, I don't see this happening. Romney is certainly a competent candidate, however, he doesn't bring much to the GOP ticket. He certainly wouldn't help McCain carry Romney's home state of Massachusetts: that's already going for the Democrats anyways. In theory, picking Romney would unite the Republican party, but in reality, I don't believe he would energize conservative voters, which would be the point of picking Romney in the first place. Part of Romney's problem during the primary was that he was seen as a political chameleon, hence core conservatives never truly trusted him. He wouldn't help the ticket bring moderates to the polls either. His so called "economic credentials" won't help out either. As I've pointed out before on this site, his record as a venture capitalist might be a liability in November, especially with unemployment rates going up. Tactically, I don't see the point of picking Romney as VP. I'm certain he's angling for the spot, but I doubt McCain will pick him. He will likely go for someone a little more closely linked to him at the end of the day.

UPDATE: I think Romney, over the past few months, has aligned himself more closely with McCain. He is clearly positioning himself for the VP nomination. As I pointed out a few months earlier in the above comment, he has some significant negatives, but broadly speaking, he wouldn't do no damage to McCain. The number 1 rule of being a VP nominee is "do no harm" to the ticket. Romney satisfies that. He's relatively scandal free; has a good record as Governor of Massachusetts; will provide the ticket with some expertise on domestic issues like health care and fiscal policy; he's a good communicator, in fact, more articulate than McCain; and while he won't energize the conservative base, he won't offend them either. But more importantly, he is capable of serving as President. People, because of McCain's advanced age, will likely scrutinize who he picks as his VP because there is a chance that he might end up as President. If McCain doesn't pick someone who can easily step into the job, his chances of getting elected will go down. So McCain cannot simply pick someone he likes, it must be someone who can serve as President. Romney will likely be the choice, given that most of the other VP candidates don't have the same credentials.