Romney's choice of VP is something he has to do that Obama can't, so it's in Romney's best interest to keep as many people guessing as possible between now and the Convention to maximize speculation.
However, the Republican talent field is so thin that this may not actually help him, but rather associate him with people he'd be smarter to run from, like Donald Trump.
The media is filled with stories pointing to Rob Portman on the one hand; or Condoleeza Rice on the other. What they seem to miss is the man himself. McCain wanted his VP choice to be a "game changer" and Sarah Palin was. Since Romney's game is less to generate excitement than to provide less of a target to Obama, he probably won't go with a surprise choice - but, it can't be ruled out. He is after all a psychopath, and such people are risk takers. An example of this was the choice of Dan Quayle by George H.W. Bush.
It took all the pundits by surprise. What is interesting is the complete absence of any speculation regarding Romney's 2008 front runner, Meg Whitman. A former Bain consultant, she knew Romney. She lost a tough race for governor of California, she has been known as a layoff queen in business, and her son's legal problems were dealt with by getting Romney's son to hire him. She hasn't been all over the campaign as she was in 2008. Does this mean she is clearly out of the running, or is this just a bit of gamesmanship by the Romneys?
She spent $148 millon on her campaign for Governor of California and received only 41% of the vote, barely 4 million. That shouldn't deter Romney though: he won the primaries with less than 10 million votes across the entire United States and he received only 4.5 million votes in his 2008 presidential run despite spending tens of millions of his money. In short, she is certainly his equal as a politician, and more than his equal as a businessperson. She also shares his values of wealth before wisdom, and if Romney is going to prove that democracy is a feeble easily corrupted thing, it is best to go whole hog with Whitman so that the public learn the lesson: it doesn't matter what THEY think, the rich have figured out how to win no matter what. Such an intimidation factor would enable his presidency.