Jack Kelly's interpretation - and I think right on target:
I suspect the attack was made more to boost morale among the faithful than to intimidate the West. With the conspicuous exception of Madrid, since 9/11 al-Qaida has been getting its brains beaten out. Showing those of waning enthusiasm that it is still strong enough to strike in the citadels of the infidel likely is worth more to al-Qaida's leaders than the negative consequences a stiffening of Western spines might bring.
However, I think that al Qaeda just made a mistake of 9/11 proportions. Especially when one includes the detinations of ordinance that took place yesterday. What do they think the Brittish military in Iraq and Afghanistan are thinking about? How bout those multicultural Londoners? Hhhhhmmmmm....
They see me,
I wouldn't be popping up anytime soon...