Great minds and horrible events
I posted about this in the 9/11 section because we're thinking similarly, this looks to me like a mini-9/11. I won't post my whole list here, but I had a different take on ultimate results.
Bottom line: In spite of the proximate results of the renewed focus on the so-called "war on terror" aka "Bush the war president's war for fun and profit", we could also see another Madrid take place in the UK. Keep in mind that over 80% of the British are AGAINST the war. The only reason Tony Blair still has his job is because of the votes for the Labour Party, not for Blair, who barely eked through.
The British could very easily see this attack as the responsibility of America because we dragged the UK into the war, and it is Bush's presence in the UK for the summit that prompted the attacks at this particular juncture. (Regardless of who promulgated the attacks.) This could force Tony Blair down more QUICKLY, force the British troops OUT of Iraq, and make the Downing Steet Memo even more damning.
Obviously, all of this is speculation, there is no way to know how it will really play out (probably some mixture of these ideas and some other unexpected events as well), and right now we do also need to consider in our thoughts the victims and their families. I do feel horrible about that, and as progressive Christian, I am saying lots of prayers today. Again, regardless of who did this.
I will feel even more horrible, however, if our hypothesis carries any weight. For that, all Americans who supported Bush should be ashamed, and those of us who didn't, many of us will also feel ashamed that we still have not been able to wake up more of our fellow citizens.