This is a good thread on Boing Boing.
Learning how to program helped me a lot, and such learning might be good for grown-ups too. Consider that the kid is going to be looking at the computer for a fair chunk of his or her life: understanding that you can have power over the fucking thing is important in addition to the logic-building skills.
First mentions were of Processing, which I have mentioned before. It, alas, has some system-specific kookiness.