Even if they don't raise the threat level, I think we will really be at pale-red between now and the November elections.
AQ has been planning to attack us in any case, then they got encouragement from the Spanish elections and are further encouraged by the Dems and Clarke's vicious attacks on President Bush.
I think they think "it's now or never" to change the course of the US. The stakes are high, they will do the most spectacular thing they can muster -- I read some reports from back in 1996-98 and the US intel was worried about AQ getting WMD even then.(
http://www.janes.com is a pre-eminent intel and defense info site -- solid stuff, no tinfoil -- most of their stuff is only for subscribers, but they do have quite a bit available free too)
The terrorists think what worked in Spain will work here -- and I am afraid to say, it may, given the gullibility of many voters and viciousness of the Democrats, who rather get elected, and have the country destroyed, than save the country.