Read the book "Saddam's Bombmaker," the autobiography of Iraqi defector Khidhir Hamza. The story is that as of several years ago, they had one or two small nukes which might or might not work. Fortunately, they're quite heavy, and Iraq probably lacks the ability to transport them very far, and they deteriorate about as quickly as the Iraqis can produce them.
The danger is real, but it's hard to be sure. This must be making US planning for the Iraq invasion even more difficult than otherwise -- all military principle says to concentrate attacking forces, but you don't want 20,000 Americans all sitting within a single square kilometer right over one of these maybe-it-works-maybe-it-doesn't monsters.
Most likely, as in the book "Is Paris Burning?" the dictator's generals will refuse to follow the dictator's scorched earth orders in full measure. However, the danger is real. I hope no one is assuming that we can use time better than Saddam can.