Well, I can see reasons not to be specific at that age. Gifted kids are not necessarily emotionally mature, and I could see a kid taunting someone else (a sibling or someone at school) by bragging about their score. Also, you son's score may change. My kid's score range is about 35 points over various IQ tests over the year (lower scores as she was older, mostly I believe due to using differen tests). But I think it would have been quite jarring for her to think her IQ was one number, then get another signficantly different number later on.
One other reason we decided to share with D15 this year is because (story told on another thread) her score (highest one, in fact) was leaked by a teacher to various members of her K-12 school community several years ago (including parents and teachers who had no need to know). She didn't know at the time, but it actually came up in a conversation with someone this year, and she asked me. It didn't seem fair that other people around her should know (besides us as parents, I think that is okay while they are younger), and she didn't.
All this said, I do think it is important to talk to our kids about the fact that they are gifted. I think they need to know in order to understand why they are different from their peers (they will surely figure out that they ARE different, and as a poster said above, they might not interpret this positively!). Also, I think it helps increase their expectations from themselves, which is mostly a good thing. I didn't really figure it out (nor did the school guidance counselor, could have knocked him over with a feather!) until I had the highest SAT scores in my county, and also an ACT score in the top 150 in my state.
