As McCain put it, the only thing worse than war with Iran is a nuclear Iran. The Iranians are hoping they can hold out until March, at which point we'll discuss the possibility of having meetings to work toward a decision on whether or not to issue a strongly worded denunciation, as lgf put it.
Militarily our airforce can do whatever it wants to Iran; things getting mucked up among Shi'ites in Iraq is the cost. (This could be an advantage -- we may have the opportunity to put down Al-Sadr for good.)
Why can't we just have the UN take care of Iran? They did such a wonderful job with Iraq!