Your phone can show others where you are

Sprint Nextel has signed up hundreds of thousands of customers for a feature that shows them where their friends are with colored marks on a map viewable on their cellphone screens. Verizon Wireless is preparing to offer a similar service in the next few weeks to its customers.

Many cellphones today have Global Positioning System technology that has been used for driving instructions, but carriers hesitated to offer tracking of cellphone users' locations because of privacy and liability concerns.

Now, increasingly, the wireless industry is deciding that location tracking has so much sales potential that it's worth the risks, so long as tight safeguards are in place. It's a result of the convergence of GPS with another digital phenomenon: a generation of young people who are comfortable sharing a great deal of personal information on social-networking Websites and eager for still more ways to stay connected. The initial target market of location-tracking services is 18- to 24-year-olds.

The wireless industry is cracking open this new market gingerly, mindful that it could face a huge backlash from consumers and regulators if location-tracking were abused by stalkers, sexual predators, advertisers or prosecutors.

Like Sprint Nextel, Verizon Wireless will use a service called Loopt, led by a 22-year-old, Sam Altman, who created the software as an undergraduate at Stanford. Mr. Altman says he is well aware of the dangers of misuse. "It's one of those things, the more you think about it, the more ways you can figure out a creep could abuse it," says Altman.

He set out to give Loopt strict rules to prevent misuse. The most significant is that cellphone users who sign up can make their whereabouts available only to a network of friends who also buy the service. They can view each others' location any time, with the proviso that users always can temporarily turn off location-tracking. The service doesn't continuously update, because that would overtax the carrier networks and consume too much battery life; it "refreshes" every 15 minutes or so, and users can always manually refresh. Altman added a couple of other rules to make the service safer. Children under 14 can't sign up. And for the first two weeks, new users are to get several messages reminding them that the service is on and that they're being tracked.

Some in the industry think wireless carriers are being too skittish. Richard Wong, a partner at venture-capital firm Accel Partners, says "operators are sometimes too careful around this issue and are stifling innovation to some degree." He says the industry isn't taking into account that younger consumers have a much more relaxed view about what constitutes an invasion of privacy than their parents. (Info from The Wall Street Journal)