The TSA is testing an electronic monitoring system that uses passengers' smart phones and other electronic devices to measure waiting times in security lines. "This technology will produce valuable data that can be used in a variety of ways," according to a spokeswoman. By logging the "chirps" emitted by some devices, the system can determine how long an individual passenger spent in line. But some privacy experts are troubled by what they perceive as an invasion of privacy. "It's serious business when the government begins to get near people's personal-communication devices," says an official with the ACLU.