Doesn't really matter any more, does it? Every time we lose sight of one of these guys, someone else suddenly becomes the major threat. To me, Bin Laden = 1984's Emmanuel Goldstein at this point. (Well, aside from the "wanting to save and help everyone" bit.)
The fact is, as long as "our intelligence" indicates that there's a single terrorist left over there with anything more threatening than a pissy letter to the editor, we've got an excuse to be there, protecting our nation from such dire peril.
(Which, I guess, is just a more cynical way of echoing what Carib said... )