>> Google has harvested the location, name and signal strength of many millions of wireless networks across the world
> Don't forget that that dataset of wireless locations is updated continuously through crowdsourcing.
Along with Apple, Skyhook, Nokia and a number of other location providers.
to make this a bit clearer, android, apple, etc devices send back wifi BSSID+GPS coordinates to the mothership for AGPS purposes. Im really suprised there hasn't been more concern about this.
As an engineering project this is truly a resourceful and rather elegant solution to tune a Kahlman filter for positioning. But on the level of privacy ... big consequences. The BSSID allows tracking when someone moves to a different place. And since that's tied to GPS with multiple captures over time you get a pretty accurate location for the WiFi device.
Along with Apple, Skyhook, Nokia and a number of other location providers.