Google Latitude is a friend-tracking tool for mobile devices; it’s also an iGoogle gadget. Using a mobile device’s built-in GPS (or manual updates), it shows the location of at least those friends who’ve added themselves to the service. See the Google Blog announcement, as well as Google Maps Mania and Richard’s Tech Reviews, for details (including which devices are supported) and context.

As with similar products (such as whereyougonnabe?; see previous entry), it really relies on the network effect for its usefulness. In other words, unless your friends are also using it, it’s kind of useless.

Gizmodo’s Brian Lam says, “I tested the service with some people I know, but it’s been hard to say if it’s useful for a guy who has loved ones in generally predictable places.” Indeed: over the past year, my location could probably be expressed as one of the following four options: (1) at home; (2) at work (which frequently is at home); (3) in transit between home and work (unless they’re the same); or (4) none of your goddamn business. In other words, services like Latitude are aimed at a certain lifestyle — urban, active, and not chained to your desk, i.e., Googlers — that may not apply to everyone.