The administration--mostly in the persons of the two who did the most to lead us into Iraq, Dick Cheney and Don Rumsfeld--is trying hard to sell America on the idea that Iran is an imminent threat that needs to be dealt with, sooner rather than later, with military action. My guess is that we'll hear a lot of these rumblings until 2008, and then we'll go in so that when November and election time rolls around, they can either claim that only Bush's hand-picked successor can be allowed to take over, or the election can be postponed in some way--and no, I'm generally not a conspiracy theorist, but with this administration I've learned that if you don't develop that attitude you're bound to miss much of what they're up to.
Anyway, here's a great post by Matthew Yglesias about what Iran's military and political situation really is, complete with links to on-the-ground accounts. Iran is a power in their neighborhood, and by supporting Shi'ites in Iraq and Hezbollah in Lebanon they're extending their influence. But a threat? Not to Israel, not to Pakistan, definitely not to the U.S.