Geolocation services like Foursquare, in their infancy a year ago, now track the whereabouts of millions of users.

一年前，像Fours quare之类的地理定位服务还处于初始阶段，但现在已可以追踪数百万用户的去向。

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But with today's cheap--or free--handsets and low-cost calling plans, many parents are handing their kids phones in an effort to stay in touch and keep track of their whereabouts.

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The device won't let you make voice calls or surf the Web, but it does offer a host of safety features: It can map a bread-crumb trail of your coordinates so that people back home can track your whereabouts from any Web browser.

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But in this case the police were able to track the phones to an apartment complex nearby, thanks to the ability of the phones to signal their whereabouts.

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