According to Frank Foer of The New Republic, there is a broad international consensus that it will take Iran about 5 years to complete a nuclear weapon. Then he reports that the CIA says it will take Iran a decade.
Funny thing - the Jerusalem Post reports that the Israeli army (IDF) estimates that Iran will have nuclear weapons in 2008, that is 3 years. Consider the CIAs failure to predict the first atomic tests run by India and Pakistan. Consider their estimates, all their estimates, about Iraq. Recall who bombed the Osirak complex in 1981. Now, who are you gonna trust?
If I wasn't freaking out about anatomy, I'd be freaking out about this.