Facebook's newest feature, Nearby Friends, begins rolling out today. The opt-in app addition lets your friends know when you're close by, with the option to show your precise location on a map, if that's the kind of thing you want to share with your friends.
Making its way to Facebook's Android and iOS app in the coming weeks, Nearby Friends thankfully works by reciprocal opt-in: you can only see friends' proximity if you allow yourself to be visible on Nearby Friends, though you can share your precise location map with a friend without him or her having to do the same. And Nearby Friends will have the same multi-mode privacy options as your News Feed, allowing you to limit Nearby Friends updates to all, some, or none of your friends.
The precise location feature allows you and a selected friend to view exact map locations for a set period of time, probably to help you and your friend find each other in a crowd. After that set time expires, you're back to standard mode, where you're alerted when friends are close but not shown their exact map locations.
When Nearby Friends rolls out to you (assuming you turn it on) you'll see a list showing the friends that are geographically closest to you who've opted in to the feature. The list includes distance away in mile increments, time of last location update, and in bigger metropolitan areas, the name of the neighborhood your friend is in. From the list, a button next to each friend will allow you to share and request exact map locations with a 40 character message, and set how long you'll be visible to them (minutes, hours, or until manually shut off). The GPS-powered feature will use your phone's accelerometers and shut off when you're stationary to try and minimize battery draw.
Facebook is following what's now become its standard practice , making this new feature a separate navigation app rather than folding it into an update to the main Facebook app. (Update: I was mistaken—Nearby Friends will be built into the main Facebook app, though it seems like the sort of feature that Facebook could very easily break out into its own app in the future.) It's also a pretty direct shot at other location-based social media offerings from the likes of Foursquare, not to mention the long-forgotten Google Latitude.
Facebook says Nearby Friends will roll out starting today. Let us know if you see it pop up. Just, please, make sure you're smart about who your sharing your location with, and when. [Facebook via TechCrunch]
Updated to clarify the permissions requirements for precise location, and to correct a mis-statement about Nearby Friends being a standalone app.