The problems of mobile phone GPS (slow/battery hungry) and operator LBS (often closed to developers) have caused people to think about obtaining location in other ways. Skyhook have created a Wi-Fi access point database and associated windows/Linux/Symbian SDK to allow developers to obtain location to within 20m.
The clever bit is that after the database has been initially created (presumably by someone from Skyhook driving around), the system and hence database self-adapts to changes by comparing new/changed access points to those with known positions.
Skyhook have a new SDK and a contest to provoke developers. You can win an iPhone or N95 – it’s ironic that they picked a GPS phone as a prize!