Sorry to makes this topic my hobbyhorse in your comments, but I think you'll find quite a literature on methods for detering Al Queda. Policy intellectuals -- left and right, but mostly right, I suppose -- often suggest that terorists are encouraged by the prospect of success, and discouraged by the prosepct of defeat. On this line, the US withdrawal from Beirut following the Marine barracks bombing encouraged terrorism -- by showing that it had the desired effect. Some Al Queda members will be beyond any rational calculation of expected gain, of course, but not all.
Of course I believe that deterrence and other "soft" methods can be effective (not totally, but still) against Al Qaeda. But I haven't heard the people nodding at claims that the Spanish have "dishonered" their dead agreeing with me about that.
Well, no one should be making 'dishonored their dead' comments, period, because such comments are vile. But I do think the general worldview of the people making those regrettable remarks encompasses the possibility of deterrence.
To the extent that I understand this disagreement, I think I agree with baa. If either the Spanish election results were driven by the bombing (and not the PP's ETA-spin) or al Qaeda members believe them to be bombing-driven, it does seem plausible that members of al Qaeda will take this as a lesson: their actions will encourage policy shifts. This, in turn, encourages more nastiness. So this could be read as a strategic victory, and the possibility of reading it that way is, I think, a dangerous thing.
That's not to say that people making this point aren't jerks about it.