From the README:
A simple GLib based program which periodically reads coordinates from gpsd. The logs directory contains a sample gps log which can be fed to gpsfake: gpsfake 1334-N-20071129-GTA01-A3.log Make sure gpsd is not running before attempting to run gpsfake. The data was taken from a Neo 1973 in central London. It will take a moment to start showing coordinates.
** edit ** This example needs updating to work on newer GPSD versions