We've opted to tell our DDs that they are very smart and that they are particularly good in math (since even in a gifted program there is a "boys are better than girls" bias about math). We haven't given actual numbers because I think that they are too young (8 & 10). I know that DD10 would get hung up on the numbers just based on her personality. I also am concerned about unhealthy comparisons with some of her hyper-competitive classmates.
For me, I never had an IQ test but I do recall getting my Iowa test results in 4th grade (9 years old). Across the board, I tested as "12th grade, 9th month." No one sat down and explained them to me. I just assumed that something was wrong with the test. I had older siblings who were in high school and I knew that I didn't know what they knew. When I tried to joke about it with my other friends, i.e. what a stupid test - I got stunned silence. It was a miserable experience.
If you do tell your DS, I would counsel him not to discuss it with his friends. You might want to do some role playing to demonstrate how most conversations about IQ with his friends are not likely to have good outcomes.
