Any Android phone has Google Maps with Latitude, which can easily be enabled and joined to another Latitude user. Once visible to each other, you can remotely turn on real time tracking. Mostly it will identify the nearest cell phone tower, giving you only a general location, if it is in a purse or pocket. Out and in use, it will pin down which side of a street a person is standing on.
For those who accidentally disabled the GPS chip, the passive location doesn’t depend upon the GPS, it reads the cell phone tower (which is a known location) as well as those mapped wifi hotspots, which can easily pin someone without GPS down to a two block area.
There is always a way around the watchers.
/johnny