[Las Vegas], famous for being America's playground, has also become its security lab. Like nowhere else in the United States, Las Vegas has embraced the twin trends of data mining and high-tech surveillance, with arguably more cameras per square foot than any airport or sports arena in the country. Even the city's cabs and monorail have cameras. Some privacy advocates view the city as a harbinger of things to come. In secret rooms in casinos across Las Vegas, surveillance specialists are busy analyzing information about players and employees. Relying on thousands of cameras in nearly every cranny of the casinos, they evaluate ... behavior. They ping names against databases that share information with other casinos, sometimes using facial-recognition software to validate a match. And in the marketing suites, casino staffers track players' every wager, every win or loss, the better to target high-rollers for special treatment and low- and middle-rollers for promotions. You could almost look at Vegas as the incubator of a whole host of surveillance technologies," said James X. Dempsey, policy director for the Center for Democracy and Technology. Those technologies, he said, have spread to other commercial venues: malls, stadiums, amusement parks. After Sept. 11, 2001, several airports tested facial-recognition software, with little success. But the government is continuing to invest in biometric technologies. "We often hear of the surveillance technology du jour, but what we're seeing now in America is a collection of surveillance technologies that work together," said Barry Steinhardt, the American Civil Liberties Union's technology and liberty project director. "It isn't just video surveillance or face recognition or license plate readers or RFID chips. It's that all these technologies are converging to create a surveillance society."