Sorry I probably didn't explain my point very well. I doubt the Skyhook database is any more accurate than Google's. To get really good triangulation you need

Sorry I probably didn't explain my point very well. I doubt the Skyhook database is any more accurate than Google's. To get really good triangulation you need an hour or so of driving round the target area (360 degrees for best results). Bearing in mind they dont drive around all that much - in a town, for example, the accuracy for individual AP's will be measured in 10's of meters or possibly more. Quite often when wardriving I will triangulate AP's to 500m or more distance from previous runs. In terms of the Skyhook service they can get much greater accuracy by using multiple access points to aggregate out the error. (Im sure their accuracy improves a little every time you get your location from the service - but I bet it's not perfect)