Bruce Schneier discusses the new TSA requirement to show one's photo ID:

The TSA has a new photo ID requirement:

Beginning Saturday, June 21, 2008 passengers that willfully refuse to provide identification at security checkpoint will be denied access to the secure area of airports. This change will apply exclusively to individuals that simply refuse to provide any identification or assist transportation security officers in ascertaining their identity.

This new procedure will not affect passengers that may have misplaced, lost or otherwise do not have ID but are cooperative with officers. Cooperative passengers without ID may be subjected to additional screening protocols, including enhanced physical screening, enhanced carry-on and/or checked baggage screening, interviews with behavior detection or law enforcement officers and other measures.

That's right; people who refuse to show ID on principle will not be allowed to fly, but people who claim to have lost their ID will. I feel well-protected against terrorists who can't lie.

Daniel Solove adds:

...[T]his rule will allow TSA officials who don't like you to have even greater power. If you lose your ID, you better hope that the TSA officials believe you, take pity on you, and otherwise think you're being cooperative. It's entirely up to them!