An excerpt from Walt Mossberg’s review of Places
In addition to testing Places around town, I paid close attention to its privacy features, to judge how much control Facebook is offering users over who gets to see where they are. My conclusion is that the controls are decent, but could be a bit better. You can control how public your Places information is on Facebook’s privacy settings screen, in the Sharing section. The default for Places is “Friends Only,” unless you expressed a preference to share things with everyone. That’s a good thing, in my view. You can change this to broaden it to, say, friends of friends, or even everyone. Or, you can limit it, so that, for instance, only certain people can see your location, or certain people can’t.
Facebook also allows you to bar others from checking you in, and lets you hide yourself from others’ “Here Now” listings, though you can’t customize this latter setting by, say, allowing only some people to know you’re nearby.