Gears Geolocation API provides a best-effort approximation (WIFI-based for PC and GPS/CellID-based for mobile devices) of your physical location.
The Gears module builds on top of the IP-based ClientLocation locator we previously blogged about. When you combine these two features together, you can create some really interesting and useful applications. Check out this demo that I put together that let you geo-search for videos nearby your current location and overlay them with Google Maps. The demo source code for this can be found here.