In the wake of a tragedy like the London bombings, it almost seems unseemly to note that it may have been preventable. Unseemly, but necessary.
Supporters of the Bush administration like to paint its critics as unwilling to take the steps necessary to combat terrorism. The truth is, we just want to combat it effectively. Invading countries unnecessarily, taking countless steps to flame anti-American sentiment around the world, and using terror alerts to political advantage are all part of a dishonest and woefully misguided mindset, one that puts many motivations higher than effective steps against the danger of terrorism.
Update: More discussion from Juan Cole, Metafilter, and Daily Kos.