Facebook is all up in Foursquare's grill with a new feature called 'Places' that allows you to share your location with your friends.
Rumours abounded as to what form the new feature would take, but Facebook Places copies the 'check in' concept popularised by Foursquare so you can easily use your phone's GPS locator to tell your friends where you are and what you're up to.
In the US only for now, users can access the service using the most recent Facebook iPhone app or touch.facebook.com if their mobile browser supports HTML5 and geolocation.
The check-in button shows you a list of nearby places. Choose where you are, or if it isn't on the list, search for it or add it. Check-ins then show up on your friends' news feeds.
Expected to move to the UK soon, it doesn't have the competitive gaming aspects of Foursquare such as badges and mayorships, but to all intents and purposes it does everything else virtually the same.
Facebook's Ben Gertzfield said, "We're working with an initial set of partners including Gowalla, Foursquare, Yelp and Booyah's InCrowd to enable users to share check-ins on Facebook. This new functionality will launch in partner applications soon."
Privacy is an obvious concern of any new location service, and Facebook said although it was possible for people who weren't your friends to know where you are, you can control what you show.
Facebook's Michael Eyal Sharon said, "In the 'People Here Now' section, you can see others who are checked in with you at that place. This section is visible for a limited amount of time and only to people who are checked in there.
"That way you can meet other people who might share your interests. If you prefer not to appear in this section, you can control whether you show up by unchecking the 'Include me in People Here Now after I check in' privacy control."
That will almost certainly not be enough to answer the concerns of parents' groups and privacy advocates. A recent brouhaha forced CEO Mark Zuckerberg to publicly repent and change his errant ways.
Places has the potential to transform the Facebook experience, with a myriad possibilities for games, dating services and sharing. How would you use it? Does the privacy aspect bother you? Is this another nail in the coffin of the concept of personal space? Let us know what you think in the comments.