Not gonna happen now, IMHO. Russia is protecting them. With nukes. The Used-and-Abused Loonie-Left stalled GWB long enough for the Russian Fascists to get their act together. Israel is the only one who could get away with it now and the US State Department is running interference for the Russians. Iran is gonna nuke a few cities before the Russkies give us the green light.
They nuke 1 city and the whole country becomes a parking lot, courtesy of a Trident sub - if, that is, Israel doesn't beat us to the punch.
Russia has assumed sponsorship of Iran and Iran will not be doing anything since that would lead directly to yet another Defcon 3 and even Russia would rather nuke Iran themselves than face that again.