Oh, and Google probably also knows where your Wi-Fi router lives

Google really does have a very big location map - and that may include where your router is. The results of its giant Street View exercise in which it took pictures of houses and shops but also gathered locations of Wi-Fi networks and - oops! - collected data from open Wi-Fi networks has all been collated.

And what's more, you can query it yourself.

Got a Wi-Fi router? Got admin access to its interface? Then you can get its MAC address and plug it into the "android map" interface offered by Samy Kamkar, a hacker and researcher who last week showed that Android phones transmit their location data (as uncovered by another researcher, Magnus Eriksson)

The page where you can plug in the details is at http://samy.pl/androidmap/, and comes with an example MAC address in there, which if you click it shows the details that are held - log/lat, country, country code, region, county, city, street, house number, postal code, and "accuracy" - an interesting idea, though it's not immediately obvious whether that's accuracy in metres or some other metric.

As Kamkar explains,

android map exposes the data that Google has been collecting from virtually all Android devices and street view cars, using them essentially as global wardriving machines.

When the phone detects any wireless network, encrypted or otherwise, it sends the BSSID (MAC address) of the router along with signal strength, and most importantly, GPS coordinates up to the mothership. This page allows you to ping that database and find exactly where any wi-fi router in the world is located.

Personally, I tried it for the two Wi-Fi routers in my home, and it turned up nothing. It could be that the data for Britain has been wiped, or that my routers weren't turned on the day Google drove by (it certainly did, because it's got a pic of the front of the house) or that it somehow didn't reach the car.

Scary? Encouraging? If all this data is somehow open sourced, is that useful or not?