I've been thinking about this for oh 25 years now but never did get around to doing it myself. Thanks to some good folks at MIT, there is now a simple graphical programming language, Scratch !
My idea was something more advanced, but this has huge advantages. The authors claim that they Kindergarten age kids have been successful at using this. I tried it out for a few minutes and am very impressed. Its certianly not going to replace "real" programming languages for complex things, but its amazing how simple it is to create apps like simple games, animated cards, talking characters. The best part is its FUN, and teach logical thinking in a way that doesnt look like "learning". I plan on setting this up for my son John and seeing if I can get him interested.