http://www.stormcam.org/gps-active/
Is it possible for someone to follow your GPS in your phone?
I have a HTC Hero, and in the system tray, it was an icon that is an animation (so you know he is active) satellite dish. I have not ever seen b4. Well, since the day I had an altercation with / genius pc, the icon appeared, never turns off. Never!
It is quite possible if they were using Google maps they could trace your cell phone, but to follow someone elses Gps I do not think its possible. It is possible Gps to hack someone elses if that is what your application, but must have the phone in their hands to do so.
Satmap Active 10 GPS – first look