NR's Byron York, fwiw:
I'm told that a number of people on Team McCain believe Obama will choose Tim Kaine. That could push the argument a bit toward Mitt Romney — a more forceful governor than Pawlenty. If Obama chose Joe Biden, that might also push Pawlenty down a little bit, but would not specifically help either Ridge, Lieberman, or Romney.
Personally, I'll be surprised if it's Kaine. (Mostly I'll be glad when all this speculation is over.)