For all the confidence; how many here have been in Iran and thus know even a little more than they may have gleaned from the 'scaremongering' and posturing in the red tops? Much of what's written there is rooted in a ... disingenuous attempt to portray Ahmadinejad as the one wielding power.
Ahmadinejad is widely and deeply unpopular, he doesn't represent broad popular opinion and his power is in decline. I agree with Flashy (et al) that there are extreme radical elements within Iran that crave a US attack, their reasons should be obvious, but they're equally unrepresentative of broader Iranian society and power broking. Remember, rhetoric hurled from the pulpit of foreign affairs is a hallmark of desperation as much as it is one of intent.
Fallon's 'resignation' removed perhaps the last significant obstacle to Bush earning himself (and, quite possibly a few of us) a fiery legacy, should he so choose. The long term repercussions aren't guaranteed, nothing is, but even given the calibre of the current US administration it should surely demand pause for thought when assessing the risk of pre-emptive engagement, the consequences of which are at surely at least as unacceptable as those some here consider would result from (to cite Kagan) - "Giving futility its chance".
Incidentally, I'm surprised no one has expanded the discussion to consider the low profile being kept by China and Russia on this building tension. A significant US intervention in Iran would be very much to their benefit, and detriment of the US and EU. That's a factor that seems to have been entirely overlooked by posters, so far.
To be fair, I've seen convincing arguments in almost direct opposition to the above, that advocate carpet bombing Iran back to the stone age, today - but here's a common theme (flaw) with many of there proponents, very few appear willing to address or even acknowledge the likely consequences. for some, hurting the 'bad guys' is clearly justification enough, even if it ends up hurting the 'good guys' more.
Who can say they know definitively the correct course of action? I know I don't and I mistrust anyone who says they do, partly because I suspect they either don't understand the issue fully and completely (no apparent consideration of Chinese/Russian advantage), or because they are unwilling to entertain the possibility of being wrong, or both.
But let me posit a single concept; the enduring stability and overriding priority of the nation state. Think about this in the context of for example, post renaissance Europe, or more recently if you prefer, the former Soviet Union. Much changed, but more stayed the same - but what motivated the sacrifices necessary to achieve that underlying continuity, despite the rhetoric?
Bomb now, pay later may have the elegance of simplicity, but the bill could kill you.