If you watched Facebook's news event, you know that the company unveiled Facebook Places, its much-anticipated location feature. This lets users "check in" to places from their mobile device and let their friends know where they're at and who they're with in real time.

To use Facebook Places at this point, you either need to have an iPhone with the most recent version of the Facebook app or access Places from touch.facebook.com if you have a mobile browser that supports HTML5 and geolocation.

Tap the "Check In" button, and you'll be presented with a list of nearby places. Then, select the place where you are. If it doesn't show up you can search for it or add it. Once you check in, it will appear in your news feed and show up in the recent activity section on the page for that place.

You can tag friends with the feature, similar to how you can tag them from status updates or photos. You can also post an update along with the check-in. There is a "People Here Now" section that shows who else is checked-in at a place.

"This section is visible for a limited amount of time and only to people who are checked in there," says Facebook Places Product Manager Michael Sharon. "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."

"With Places, you are in control of what you share and the people you share with," he adds. "You choose whether or not to share your location when you check in at a place. When you check in, you can tag friends who are with you but only if their settings allow it. When you are tagged, you are always notified." For more on the privacy settings, read Facebook's announcement.

You can share your check-in info with third-party apps to make other services relevant to you. Friends can share your info with apps unless you turn it off.

If privacy is a concern for you, go check your settings now. You'll have to uncheck some boxes.

Naturally, there is a whole lot of discussion about the feature out thee. Techmeme has a wide sampling.

Currently, Facebook Places is only available in the U.S.