Official Google Blog: See where your friends are with Google Latitude

A snapshot of new Google capabilities that are likely to be controversial

Fun aside, we recognize the sensitivity of location data, so we've built fine-grained privacy controls right into the application. Everything about Latitude is opt-in. You not only control exactly who gets to see your location, but you also decide the location that they see. For instance, let's say you are in Rome. Instead of having your approximate location detected and shared automatically, you can manually set your location for elsewhere — perhaps a visit to Niagara Falls . Since you may not want to share the same information with everyone, Latitude lets you change the settings on a friend-by-friend basis. So for each person, you can choose to share your best available location or your city-level location, or you can hide. Everything is under your control and, of course, you can sign out of Latitude at any time

Official Google Blog: See where your friends are with Google Latitude