There was no accompanying demand with this attack. The attack itself was the point, and it was meant to inflict maximum damage to the country.
I think he may have given it his best shot.
The idea (I suppose) would be to strike a massive blow, then make the bombs' presence known to key US officials. That leaves the US to decide between attacking a risking tens of millions of lives or doing nothing and being seen as weak and humiliated.
All that said, I don't believe Bin Laden has working nuclear weapons - he may have components. And regardless, we must strike now or live in fear forever.
I'm not convinced of that. All the more reason to be vigilant.
If so, then he's dumber than he is evil. Either that, or he exponentially underestimated American resolve.
I suspect he's got alot more tricks up his sleeve -- maybe not nuclear, but tricks nonetheless.
And another thing I suspect you can be pretty sure of: He's not in Afghanistan.