Doesn't Google have a database of all WiFi access points and their relative GPS location? It's one of the things they recorded when they did StreetView if I'm not mistaken, to aid faster GPS as WiFi access points typically have a fixed geographical location.
I know because if I turn on GPS with WiFi off it takes 10-30 seconds to get a fix, and it gives you a message saying you can get faster fix if you turn on WiFi. If you try to get a fix with WiFi on it get's a fix within a second if your in range of a WiFi access point.
I know because if I turn on GPS with WiFi off it takes 10-30 seconds to get a fix, and it gives you a message saying you can get faster fix if you turn on WiFi. If you try to get a fix with WiFi on it get's a fix within a second if your in range of a WiFi access point.