Anyone interested in the question of Iran's acquisition of nuclear weapons and what can be done about it (and I assume that is most of you) should take a look at this thoughtful post by Noah at Gideon's Blog. Noah supported the Iraq war and is a strongly pro-Israel right-of-centre American Jew, so the mere fact that he is against attacking Iran has a certain newsworthiness. More importantly, the analysis is really good.
I find myself in a somewhat difficult position here. To me, nuclear non-proliferation genuinely ought to be right at the heart of American and Western foreign policy. Up until the Bush administration, the Nuclear Proliferation Treaty worked better than anyone had a right to expect. This was good for America, of course, but it also benefited the world overall. It is not that a new nuclear power would immediately use its weapons. But it would use the diplomatic advantage, and its rivals would end up developing nukes too. It would not take long until pretty much all serious states had nukes: that would probably reduce the occurrence of conventional warfare, but sooner or later something would go wrong. It is true that the NPT does not itself authorize the use of force for contravention, but even though I take international law a lot more seriously than most American foreign policy types, I can't take it that seriously. If a hostile state is violating its obligations under the NPT, then force could be justified.
At the same time, I agree with Noah about the downsides of an attack that he foresees, and I suspect there are many that are not foreseeable. Noah says a conventional bombing attack would not be effective in neutralizing Iran's nuclear program: he may be right. I have no specialized knowledge or insight into this military question, except that this seems like the kind of thing the US military IS good at. (The occupation of Iraq demonstrating what it is terrible at.)
Ideally, force would be kept as a last resort, while the West engaged in brilliant diplomatic maneuvering, pushed Israel to give Palestinians a genuine state and to come clean about its own nuclear program and gave Tehran diplomatic recognition. Unfortunately, we live in the non-ideal world of a Bush administration, and the Baker/Scowcroft coup I have been hoping for since 2003 has yet to materialize. I suspect that any actual attack by this actual group would be a disaster, but I wouldn't want the US as a matter of policy to rule out an attack altogether. I feel kind of stuck.