I have read a very interesting article by STRATFOR two weeks ago that was talking about the whole torture process, the morality involved and the utility it brings to intelligence gathering effort.
First of all, the hypothetic situation that: "Do you torture a man if you know he has the bomb that will come off in the next hour?" is a very, very, very restrint situation. If you do know that:
1) There is a bomb that will go off
2) The general area where it will explodes
3) Who knows about it
4) The time it will explode
You already won the intelligence war; your intelligence network worked perfectly. Torture will simply be a mean to quicken the inevitable. If you do have the time to deal with the guy, it's usually much more efficient to show the guy all that you know, and tell him that he will never leave his cell anyway.
But those kind of circumstances are not common. In the aftermath of 9/11, the USA Intelligence agencies panicked, because they were caught unaware. The general intelligence network had been on sleep duty since the end of the cold war, and weren't paying much attention to groups like Al-Qaeda. But when AQ striked, they realised that they had a new ennemy that they didn't understand. They didn't understand the motivations, their means nor their objective.
Everybody was afraid right after 9/11, and for good reasons. The lack of information about the ennemy and its capability (specially knowning that AQ was reknown for it's 1-2 attacks) forced USA and its allies to resort to... less than mighty means. Yes, torture. They needed to understand the workout of the islamic terrorist organisations, and they did. The counter-terrorism effort is now much, much, much more efficient at dealing against those organisations, because we understand them a lot more now.
But in the meanwhile, torture passed from an emergency measure to a regular routine. It has became common place for U.S. intelligence agencies to resort to these means to gather information. And we aren't talking about life-or-death intelligence, we are talking about basic intelligence gathering. There are much more efficient (both in term of the quality of the information, and the PR involved) ways of using prisoners when you are doing routine interrogation.
So, am I in favor of banning torture for our intelligence missions? No. Nor I am in favor of banning nuclear weapons. It's a tool that has its uses, both in the extreme measures and as a dissuasive when you get into "intensive" interrogation. You can use it as a treath. But same than nuclear weapons, it should not be the norm. It should be exceptional. In times of pure crisis or when time is the essence - but then again, if you know the points 1, 2, 3 and 4 of what I wrote up-there, you have a pretty good intel network, don't you think?
To torture effeciently, you need to know who knows.