I don't really agree withyou there an0n. With maybe a few, small exceptions, I'd be willing to bet European leaders'll ignore this one. For one thing, the "We do not negotiate with terrorists" line is beaten into every major western government these days pretty solidly, moreover, if people are willing to separate this from Iraq, then it's still sitting back and treating these people like anything other than the evil buggers they are. Do you think the spanish are just going to say "OK, all is forgiven, let's all just get along!"? I personally doubt it.
Also, the US will condemn this faster than you can say, well, much of anything, and in political and economic terms, keeping the US happy is more important than keeping terrorists happy, especially since, all things considered, these attacks aren't really killing that many people (Compared to the normal definition of war - I mean, compare the casualties from September 11 or Madrid to Pearl Harbour or Galipolli). If Al Quaeda were killing people, from dozens of European countries on a weekly or monthly basis, this might get more consideration, but really, per country, a major attack can be expected, what, every 20, 30 years? Given the average casulaty lists, that's comparable to the road toll. Bin Laden just doesn;t have the negotiating power in this particular situation.