It is interesting, Skyhook for example claim to have mapped many wifi networks using cars trolling around the streets. Google tried to do the same thing and got into trouble for it.
There must be something else in play though. I recently (well 8 months ago!)moved from one flat to another. They are about 1.5 miles apart. Because they were on the same telephone exchange I had my entire BT service transferred, number, BT Broadband and all. This was very quick, the service was still active at the old place as I was tidying up the last few things, listening to streaming radio on an iPod connected to some speakers. Then the music went dead, checked the line it was dead too. Drive up to the new place with all the Homehub and gubbin's, plugged it all in and hey presto all working in the new place.
The odd thing is the iPod Touches reported the right location in the new flat straight away, and I am certain no Skyhook or Google cars followed me up the road!
