Professor Alessandro Acquisti of Carnegie Mellon, who researches how technology impacts privacy, stunned Stahl with an experiment. He photographed random students on the campus and in short order, not only identified several of them, but in a number of cases found their personal information, including social security numbers, just using a facial recognition program he downloaded for free. Acquisti says smart-phones will make "facial searches" as common as Google searches in the future. And nearly everybody can be subject to such prying, even those who are careful about their Internet use.

Companies are beginning to use facial recognition technology to improve business. National retailers are installing cameras, some in store mannequins, to learn more about customers, while entities like malls can put cameras in digital billboards that recognize the age and gender of their shoppers and tailor ads to them on the spot.