Gallup asked this question last night, after the London bombings:

How safe do you think you and your immediate family are from attacks similar to the ones that occurred in London today -- very safe, somewhat safe, not very safe, or not safe at all?

Eigthy-three percent of those responding said they felt "very safe" or "somewhat safe." It's not clear whether that's because the people polled have changed their behavior to avoid crowded trains, to drive instead of fly on their vacation, or to move to some undisclosed location.

Gallup also asked this question:

Would you favor or oppose requiring every American to go through a metal detector when using public transportation, including trains, buses, or subways?

Predictably, 69 percent answered "favor." Given that until yesterday a lot of people had long gone back to carping and complaining and tcching over security lines at airports, it's doubtful that number will last more than a few days.