UPDATE: Found the mechanism was actually floating around in mid 2011 – Hans Lemurson’s video: http://www.youtube.com/watch?v=s7hbOeQjbFI
This is a simple Minecraft robot that drives along a powered track. The track supplies timing signals. PuMPY can push 11 blocks the length of the track. The robot is 1xPiston and 1xSticky Piston placed facing each other on the track.
Thanks to Redditor Chronophilia for the comment that gave rise to this.
Duration : 0:2:1