[angusgr]

Has anyone looked at the coordinates in the Wifilocation table?

For cell towers, iOS has access to coordinates from the tower's signal itself. For Wifi, the best approximation would be the GPS location of the device. Unless it associates Wifi APs with nearby cell towers, or "fuzzes" that location.

[evan_]

iOS uses skyhook (or a workalike) to turn wifi MAC addresses into geospatial locations.