The half-billion people registered on Facebook are free to give up a little more privacy. The social networking site launched has ia new service dubbed “Places.” With just a click on a button, you can let your Facebook friends know where you are around the clock via mobile phone.

Whenever you get anywhere—Starbucks, let’s say—you just click on check in, and all your friends (and stalkers) will know exactly where you are. Your location will appear in their News Feeds, and you will show up in the Recent Activity section of that place’s Facebook page.

At a press conference at Facebook HQ, the company praised the benefits of the new app, explaining that it will enable to friends to meet up whenever they happen to be nearby. If they know you are next door in Starbucks, for instance, they can pop in for a coffee and a chat.

Facebook also said that companies will be able to reward frequent visitors by offering them discounts and other swag. For instance, frequent visitors to the coffee chain will be called “mayors of Starbucks” and receive a $1 discount. And ten years down the line, someone will know that at 9:30 am on August 19, you were drinking coffee at Starbucks when you should have been at work.

Given its recent privacy fiascos, Facebook has taken great care to ensure that users do not feel that their space has been too invaded. The default setting lets only your “friends” know where you are, and users can choose to limit even that list. On the other hand, the Twitterati-types will be able to let people know exactly what they are doing at any time in any place, and even expound on the intense emotional rollercoaster that sipping a macchiato leads to.

To quote the Facebook blog, “If you’re like me, when you find a place you really like, you want to tell your friends you’re there. Maybe it’s a new restaurant, a beautiful hiking trail or an amazing live show. … with Facebook Places. You can share where you are and the friends you’re with in real time from your mobile device.”

Ironically, the news came out just as Google’s Eric Schmidt was warning people: “I don’t believe society understands what happens when everything is available, knowable and recorded by everyone all the time… I mean we really have to think about these things as a society.” Schmidt wasn’t referring to Facebook per se, but rather to his own company’s foray into the world of social networking. As early as last year, Time Magazine featured an article on how lawyers consider social networking sites to be “evidentiary gold mines.”

With Facebook’s new “Places,” it’s almost as if they blasted off the mountain top and fracked miles beneath the surface just to get at the nuggets.

Schmidt believes that sometime in the not-so-distant future, young social networkers may have to reinvent themselves at some point in their lives, just to “escape the ghosts of their online past.” What Schmidt didn’t mention is that even a simple act like uploading photos to your social networking site, can already provide the less scrupulous among us with information about your GPS location. In other words, “We know where you are.”

Facebook Places was launched in conjunction with FourSquare, Gowalla, and Shopkick.
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