I agree that the interest needs to be there. When I was 10 I taught myself BASIC, moved on to Pascal by 12, Assembly at 14, over to C, back to Java, etc, etc, etc. Once a programmer gets their feet wet with a couple different types of languages the sky is the limit, but something has got to "click" early on or it's just not going to work.
I wish Logo were still available, because that would be perfect--instant gratification is what kids at that age like. You may even want to look at Macro programming in some of the MS Office apps since it provides fairly instant feedback in a controlled environment.