Josh Marshall has a scoop:

There is chatter in Pakistani intelligence circles that the US has let the Pakistanis know that the optimal time for bagging 'high value' al Qaida suspects in the untamed Afghan-Pakistani border lands is the last ten days of July, 2004.

Gee whiz, what could possibly be going on during the last ten days of July?

UPDATE: Swopa throws a little cold water on the "they're just waiting for the most politically expedient moment" theory, noting that this is coming from the same people who have completely bungled and mismanaged Iraq.