In a recent presentation at BlackHat Europe, two Oxford University academics revealed significant privacy flaws in the set up of mobile networks, allowing anyone to track mobile phones using a WiFi-enabled laptop, or other WiFi device. The work of researchers Piers O’Hanlon and Ravishankar Borgaonkar shows how to use WiFi to perform the same role as an IMSI-catcher, though their technique only permits the tracking of the phone and cannot be used for the interception of voice or data.
A synopsis of the presentation is available at the website of the Oxford University CompSci Department; see here. The full slide pack can be found at the BlackHat conference website; look here.