First of all, Iran is HUGE, so it is doubtful anything will happen via "precision" bombings. They most likely have MANY underground nuclear research facilities.
In response to an attack, Iran will instantly target all US and Israeli ships in the Persian Gulf, and maybe even shut down the gulf, causing our gas and power prices to skyrocket.
You also have to imagine Russia and China will not be very happy, and North Korea will feel even more pressure to do something pro-active, as it watches the second of the 3 "axis-of-evil" countries getting attacked.
Nothing good will come from going to war with Iran... no way!