The Coyote Roller http://www.coyoteroller.com/ is not available in Australia though can be sent from the USA.  

The Australian version, The Oscillot, was featured on the New Inventors in 2007. It consists of a four paddled rod which sits across the top of the fence and spins when the animal jumps up to go over. They get thrown safely back to their own side of the fence. On their web site they do not guarantee it for deterring animals other than cats.