IQ tests are just a snapshot of the brain at a given time. OP, it is quite possible that your son did not test well on the WISC on that particular day and that he is very gifted in spite of the level of his IQ score.
as to what an IQ score gets you: in our case, there was no tangible "reward" from having a score - except that I, as a parent know that there is latent ability in the child and there is a pressing need for differentiation and opportunities. I, as a parent, try to do the best that I can with regards to finding those opportunities. Our local school system does not provide gifted programming because of various disputes and lawsuits by parents, so the IQ numbers are not useful in that setting. But, they provided a good basis to advocate in a private school setting.
