while I regard this report to be bogus - I would have to guess that normal media outlets would have picked up on something....are any of our government's leaders traveling now? Bush is in Texas, the House and the Senate are on a break...all pre-scheduled though.....and would you pick a Saturday to maximize targets?
the premise isn't that far-fetched or ridiculous.
I completely agree that Al-Q isn't capable of making their own nukes - but I would certainly think that they would have been able to afford buying a few from any number of rogue sources with access to the former Soviet Union's arsenal, or from their close friends in Pakistan. It is also likely that any degredation of the timers/detonators could be rather easily repaired by any number of Pakistani weapons experts, who have their own little nuclear arsenal.
I can't say with any certainty how hard it would be for someone to get a small truck across the southern US border and into one of the cities listed here, but I'd guess it's quite possible.
As for suitcase nukes, I'm not sure their existence has ever been verified, but if it's true, then that just makes a weapon such as that much easier to get into this country.
Sadly, I think that tomorrow isn't going to be an 'American Hiroshima', but I think that some point in the near-future (next 6-10 years) we may well see such a device used to in a major city..and god help us all after that.