GPS is great at locating you anywhere on the planet, to within ten feet or so. Problem is, it only works where the receiver’s antenna can see the sky. Indoors, it’s useless. Place Lab Software wants to change that:
Place Lab is a software base and a community-building activity that facilitates widespread adoption of low-cost, easy-to-use user positioning for location-enhanced computing applciations. Unlike existing indoor and outdoor user-positioning systems, Place Lab endeavors to provide planetary-scale and privacy observant user positioning by making use of existing infrastructure and offering a low barrier to participation. Furthermore, Place Lab allows clients to determine their location entirely privately without constant interaction with a central service.
The key motivation for Place Lab is the widespread proliferation of WiFi technology. Based on the IEEE 802.11 standard, WiFi hotspots are now mainstream — at homes, enterprises, university campuses, and in public spaces in many cities and towns around the world. Leveraging this ubiquitous deployment of WiFi access points, Place Lab provides a way for a WiFi-enabled client device to automatically determine its position. Place Lab exploits the fact that each WiFi access point has a globally unique MAC identifier that the access point periodically broadcasts as part of its management beacon. Combining these beacons with a service that maps MAC identifiers to (latitude, longitude) coordinates, Place Lab allows client devices to passively listen for nearby access points and triangulate their own position based on the positions of these access points.
Cool stuff, and you can download the free client for just about any platform from their site, including Pocket PC. The download is prety hefty at about 25 MB, though. Check it out.