Here is a video on a very early pulse proportional radio control system developed by the Germans during WWII called the Fritz-X. This was used in a early "smart weapon" to control a bomb. The control system was 3 axis, up/down (to control distance of flight), left/right (to steer), plus a gyro controlled roll so that the other two axis of controls worked as intended. The last 5 minutes of the 15 minute video shows how the control system worked, as the tail control surfaces did not move, but rather changed the lift of the tail surfaces with spoiler blades that moved in and out of the airflow. The Germans thought that a controlled bomb was 80 times more likely to hit it's target, but it was also fairly easy to jam the control link.
No doubt pulse proportional control is a very old concept, but getting 3 controls from a single motor is what make a GG system so amazing.
http://www.youtube.com/watch?v=t1imE2GwDK8