N!NJA writes: Few devices know more personal details about people than the smartphones in their pockets: phone numbers, current location, often the owner's real name — even a unique ID number that can never be changed or turned off. These phones don't keep secrets. They are sharing this personal data widely and regularly, a Wall Street Journal investigation has found. An examination of 101 popular smartphone "apps" — games and other software applications for iPhone and Android phones — showed that 56 transmitted the phone's unique device ID to other companies without users' awareness or consent. Forty-seven apps transmitted the phone's location in some way. Five sent age, gender and other personal details to outsiders. Among the apps tested, the iPhone apps transmitted more data than the apps on phones using Google Inc.'s Android operating system. [...]
"The great thing about mobile is you can't clear a UDID like you can a cookie," says Meghan O'Holleran of Traffic Marketplace, an Internet ad network that is expanding into mobile apps. "That's how we track everything." Ms. O'Holleran says Traffic Marketplace, a unit of Epic Media Group, monitors smartphone users whenever it can. "We watch what apps you download, how frequently you use them, how much time you spend on them, how deep into the app you go," she says. She says the data is aggregated and not linked to an individual. [...]
Some developers feel pressure to release more data about people. Max Binshtok, creator of the DailyHoroscope Android app, says ad-network executives encouraged him to transmit users' locations. Mr. Binshtok says he declined because of privacy concerns. But ads targeted by location bring in two to five times as much money as untargeted ads, Mr. Binshtok says. "We are losing a lot of revenue."