Opinion Facebook has added a My Location button, initially just to the iPhone client. But why would you want everyone to know where you are, and how can you prevent that happening?
Facebook now wants to know where you are, or at least where you'd like people to think you are, and expects your friends to shop you if you don't bother checking in yourself. The more exhibitionist user might be happy for everyone to know their location, but the rest of us need to delve into our Facebook settings to turn off the new feature.
The new iPhone Facebook client (in the App store) already has Places built in, and it won't be long before it spreads to the other mobile platforms. But even if you've no intention of telling everyone where you are you might find that someone else is doing it for you.
The obsession with sharing afflicts a generation to whom Facebook is an integral part of life, who update their status with such regularity that Places is automating an already-familiar process rather than doing anything new. Similar service Foursquare offers much the same functionality, through a dedicated app that integrates with Facebook and Twitter, but reckons that Facebook Places won't hurt its business.
Foursquare provides an incentive to keep updating in the form of virtual awards. Be the Foursquare user who visits a location most often and you are declared 'Mayor' of that location, a position with no salary but the respect of your peers (assuming your peers respect that kind of thing). A place that gets 50 users checked in within an hour gets awarded with a "swarm badge" - apparently highly valued by Foursquare users.
Facebook users are already comfortable with virtual rewards and gifts so this kind of model will no doubt quickly spread into the Facebook world. Foursquare reckons that Facebook Places will complement its service, and it will certainly want to integrate as closely as possible to avoid being sidelined.
But not everyone will be happy sharing their location or having it shared for them, and while the options to switch off those services do exist they are far from obvious. You might feel that the lack of GPS on your phone will protect you, but that won't stop those you know reporting where you are.
Assuming you've not just disconnected from Facebook entirely, you'll need to go into Privacy Settings, and then click on "Custom" and "Customise settings". Here you'll find the three settings you'll want to change. The first is sharing of "Places I check in", which you can make visible only to yourself (just in case you check in accidentally). Next you might want to disable "People here now" flag - again that should only be an issue if you accidentally check in, or fancy using Facebook Places but not appearing on lists of people nearby.
Lastly, and probably most importantly, scroll down and disable "Friends can check me in to places", just to make sure that no one decides to use the service on your behalf. ®