It could be that they want to wait until after the election. If they do have Zarqawi detained, they could use him to quell attacks leading up to and during the election.
Yes, "more info", "election timing", makes sense. Although, I would think if they really did have him the news of that would be near impossible to keep secret. In any event, I hope the "no comment" is not out of embarassment "for letting him go" as an earlier poster mentioned. That's one scenario I wouldn't care to think about.
We shall see..