Here's First Read:
“I’m appreciative every time I see Mitt on television on my behalf. He does a better job for me than he did for himself as a matter of fact.” Bada bing. If McCain can start joking about someone, you know they've made it into his mental inner circle.
This is correct, I think.
First, he's a solid communicator on domestic policy, complementary to his would-be boss, who isn't. This election -- it seems more clear by the week -- will be won by the guy who is most plausibly a Mr. Fix-It. McCain needs help inside the contiguous 48.
Romney passes the threshold commander in chief test, he would be a plausible governing partner for McCain, his shop would never leak, he would do what McCain asked of him, and he's generationally appropriate: where McCain physically recoils at questions about, say, sex and culture, Romney can diffuse them with a joke.
In any event, people around McCain do not discourage speculation that Romney's stock is rising.
Logistical note: Romney will attend the Beijing Olympics next month, so if McCain wants to announce his pick early, he may want to adjust his schedule.