From today’s NYT:

If American forces found Saddam Hussein hiding in an eight-foot deep hole in central Iraq, why have they not found Osama bin Laden or the fugitive Taliban leader, Mullah Muhammad Omar?

Asked this question, American, Pakistani and Afghan officials and terrorism experts note immediately that the searches are enormously different.

Well, yes. One search involved looking for an old, fat, beared man, located in a small, mostly flat region of a smallish country. The other search consists of trying to identify smeared particles in a cave somewhere.