Carnegie Mellon has developed a tool called Alice, for kids and other children to learn how to use object oriented programming. The tool allows you to programming figures in a virtual 3D world. Its not rocket science, and if one need to learn programming one would probably move on quickly, but hey its fun, and introduces the concept.
Wonder how early a parent can start :)
In fact after looking a bit on the net, there is also other alternatives. Here is one from MIT research lab http://scratch.mit.edu/ which is a bit more complicated.