Steven Clemons lays out a persuasive case that in a military strategic ops meeting Bush was persuaded that if he ordered an attack on Iran they could not guarantee that all of Iran's nuclear facilities would be taken out and blowback from the operation would be harmful to the United States.
The attack seems to have been placed on hold. I believe that Bush will reconsider, perhaps next year. Right now Bush is using other means to attempt to overthrow the Iranian government.
There is still great danger as many influential people are working to get the United States to attack. Cheney and the other rabid war hawk neocon's are not taking Bush's decision well, of course. There have been a number of leaks since early this year of Cheney and his staff's unhappiness and other neocons have publicly advocated attacks and called conferences to make that seem the only option.
Of all places Reason Magazine has a good article by Michael J. Totten on some of those other means - revolution not invasion, that Bush has turned to.
As Joe Klein at a Time blog post back in March revealed Bush accepted the military's Iran advice but rejected their other advise and went ahead with the troop surge.
Based on the movement of carrier groups and bomber air wings Bush has left the option open to change his mind at any time.
I fell like I am in the Cold War or the dark days of WW2, sifting for clues as to what the hawks in the Kremlin or Berchtesgaden and the Eagle's Nest were going to do next.