Just because Facebook has moved on to virtual reality face gear and drones doesn't mean they've forgotten their core competency: stalking. The company just launched an optional "Nearby Friends" feature that will let you "continuously" track friends like they were Jason Bourne.

Users can decide whether Facebook reveals your location down to the half mile or as close as they can get using GPS and triangulating between cellphone towers. The results must be awfully precise because Facebook thinks the best use case is finding people in airports, shopping malls, and parks, using the map to "walk directly toward them."

Facebook is notorious for forcing users to opt-out of a service, but "Nearby Friends" is voluntary and opt-in. However, in the past users have also had trouble with opt-in features, like automatically uploading iPhone photos to Facebook. Friends of this conservative British politician have the NSFW dick pics to prove it.

"Nearby Friends" only works if both parties turn the service on and if you elect to share the information with them, but spending time with pals has never sounded so ominous or required so many privacy settings. For example, the map above doesn't depict a bunch of people, but an individual's activity log that they will have to remember to delete, according to Business Insider:

To prevent stalking, the function comes with a timer that switches off Nearby Friends after a certain time, for instance one hour. And only friends can see you in Nearby Friends — not friends of friends or members of the public you have not confirmed as friends.

Nearby Friends also produces an activity log, which you can delete at will. The log also produces maps of your whereabouts over time, which you can also delete if you want.

Facebook hasn't had much success getting users to reveal where they are before. Facebook Places, an attempt to kill Foursquare, ended up slightly more popular than Facebook Poke, a failed attempt to kill Snapchat. Instagram recently started experimenting with using Facebook Places. The scenarios outlined here also veer into Foursquare territory, only Facebook's got a billion more users:

When Nearby Friends is on, you can see when your friends are traveling if they're also using this feature and sharing with you. You'll be able to see the city or neighborhood they are in, including on their profile. When you see a friend visiting a place you've been, it's the perfect opportunity to send a recommendation for a great restaurant. You can also make last-minute plans to meet up with a friend who happens to be in the same place you're headed to.

Like Instagram, Oculus Rift, and WhatsApp, this feature is also the result of an acquisition as Facebook tries to become the next Google. Former Glancee CEO and cofounder Andrea Vaccari, who now works at Facebook, assures Business Insider that all this information about exactly where you've been is not being sold for profit.

Obviously, the new feature has the potential to produce a lot of new data on users. Facebook product manager Andrea Vaccari says that, currently, none of that data will be used for purposes outside the app. It will not be used to help target advertising, for instance. And Nearby Friends will not be usable by business Pages that you're fans of — so local restaurants and stores won't be pinging you with offers when you walk by. (Of course, given Facebook's track record, it would seem natural that such a useful new trove of location data might eventually be monetized in some way in the future.)

The operative word there is "currently."

To contact the author of this post, please email nitasha@gawker.com.

[Top image via Business Insider; other images via Facebook]