They're used to track toll passes and merchandise. Virginia might put them in drivers' licenses, and Japan is putting them in students' backpacks. Radio Frequency Identification trackers solve many problems. But we learn how they create some new ones, too. Hear NPR's Neal Conan and guests including NPR's Larry Abramson, Jack Grasso, senior director of public relations for EPC Global, Mark Walter, chief technical officer at the Enterprise Charter School of Buffalo, and Barry Steinhardt, director of the ACLU's technology and liberty program.