Intel is experimenting with WiFi networks to develop a location-based system using WLAN access points and cell towers to triangulate location. GPS is often useless in large urban settings, especially in so-called urban canyons. Location technology that uses cell networks and WiFi networks could act as replacement, or supplement, for GPS in dense urban areas. There are other technologies currently on the market, like Cambridge Positioning Systems, that offer similar location services using GSM infrastructure.
For more on Intel's cellular/WiFi location tests:
- view this piece from CNET