The lead story on Politico is about Romney's 2012 team on hold but it concludes with this.
The consensus among those close to Romney is that his oft-stated mantra about “not closing the door” on a run is about right – he’s watching Obama closely and would be inclined to get in if it seemed like he had a realistic path to victory.
Read more: http://www.politico.com/news/stories/0609/24316_Page3.html#ixzz0JpfKrCn0&C
That more than anything else I've seen suggests the possibility of Romney not running is real. His 2008 run cost him a lot of his own money. Right now polls show Obama with a double digit lead head to head against Romney. If a year and a half from now the economy shows signs of recovery, the Republicans fair poorly in 2010 and Obama's approval is still sitting above 60, I wouldn't be stunned if Romney passes on 2012.
1) The problem is, he'll have to decide by about February 2011, and that's too early to know if Obama will be vulnerable. If you judge by polls from two years out, then GHW Bush wins a landslide reelection victory in 1992 and Bill Clinton loses badly in 1996.
2) Even if Romney is pretty firmly committed to running, there's nothing to be gained by telling people about it, even in private. He's better served by strategic ambiguity.
So I still think there's a >85% chance that Romney runs. Probably higher probability of him running than anyone else in the field. Higher than Huckabee. Higher than Palin. Higher than Pawlenty, etc.