The tool, penned by a Melbourne-based researcher potentially can track where all the Apple users live so that you can give them wedgies and mock their poor technology decisions. The tool works by accessing Apple's database of wireless access points, which is collected by iPhones and iPads that have GPS and wifi location services enabled. Since iPhones and iPads regularly submit information about access points within range to Apple, regardless of whether users connect to them it is easy to tap into the information.
The location database is not meant to be public, but since this is superior Apple networking technology it is wide open to any hacker. Hubert Seiwert said that Apple will reveal MAC address and GPS information on hundreds of nearby access points if a user queries the location of a single wifi router's MAC address.
His proof of concept Python application, iSniff GPS, uses this process to allow users to view maps of nearby access points.