Google has just introduced a rather neat new feature in Google Gears: WiFi geo-location.
Essentially, the way it works is this. You opt-in for the service on Chrome, Internet Exporer, Safari or Firefox, with the usual privacy caveats (although Google denies recording your information). At that point, Google will automatically triangulate your position within "200m of accuracy" in hundreds of cities. This allows you to use location-based Internet apps with ease: for example, just go to a webpage and get nearby restaurant recommendations, or see promiscuous girls near you.
How's it done? Google's not saying, but Ars posits its much like existing WiFi positioning done by Skyhook, which works by sending fleets of vehicles with extra-sensivtive GPS and WiFi receivers driving around cities. This could be accomplished with Google's existing Streeview vehicles. From there, when you log-in, Google would simply compare the data of the WiFi hotspots in view of your computer with its database.
This is pretty cool. I'm a big fan of location-based apps on the iPhone like Nearby and would love to see more websites support this sort of thing. Let's see if Google makes any real headway with it.
Google Gears enhances geolocation with WiFi positioning [Ars Technica]