"This is a definite prelude to attack. Proper islamic protocol requires an opportunity to convert before an attack."
My thoughts exactly. Maybe AQ wants to celebrate the 5th anniversary of 9/11 with a "bang"?
I don't think they'd have any chance of getting away with it on 9/11. Security is going to be really, really high everywhere. I think they're more likely to try for sometime when they think we have let our guard down and are distracted with something else. (Election Day, for example?)