I recently got my invitation to join the beta test of Fire Eagle, a new location-tracking service from Yahoo. Now, technically, it doesn’t “track” where you are, but rather, when you tell it where you are, it listens, and then shares that information with other online applications that you approve. The more apps you plug into it, the more useful it is.

For example, an app on my iPhone could monitor my geographical location and ping Fire Eagle with an update every so often. So iPhone says “now he’s in New York,” and Fire Eagle updates its record. Then, say my weather-tracking app checks with Fire Eagle, which tells it “last I heard, he’s in New York.” So the weather app says “cool, thanks” and then presents me with the forecast in NYC automatically, and I go “whoa, how did you know I went to New York? You’re just a silly weather app.”

Fire Eagle bills itself as “the secure and stylish way to share your location with sites and services online,” and so far, I’d say it lives up to that promise. Although it’s essentially just a database that tracks only one thing (your location), the more applications and devices that become “location-aware” by connecting to this service, the more useful it will become.

I should mention that, of course, there are huge privacy concerns (or should be) whenever people voluntarily share their whereabouts with a corporate entity, but Yahoo swears that they retain only your most recent location and no historical data. (Of course, other services that you authorize to access your Fire Eagle data may retain the information longer.) I appreciate that the UI even has a “My Privacy” page that enables you to temporarily “hide” yourself and ostensibly delete all your location data from Yahoo servers.