GPS Badges?

Well, not quite yet, but maybe soon:

• Police departments in South Carolina and Massachusetts are testing a radio frequency identification system to manage badge inventory and department security better. Both are testing the SmartShield system, which consists of officer badges with embedded RFID chips and a records management software application known as Enforcement Identification (Eid).
  
  Developed and marketed by V.H. Blackinton & Co., SmartShield can be used to track badges as they leave a storage area for assignment to officers. RFID interrogators (readers) are not included in the package, but by the time the system becomes commercially available in August, they might be, according V.H. Blackinton's John Domurad, director of research and development. "They're in development," he says.

It's an older article (2006) and the RFID is more for scanning you into and out of secure areas. But the data is logged and trackable and would seem to to be completely fitting with the direction the Department is going lately.