Well, I don't think autism is retardation, etc... It is almost like a computer with a memory mapped video card. Reducing the video memory means more memory/speed for the computer. Likewise, autistics have fewer resources dedicated towards social stuff, and other stuff benefits. BESIDES, aspies work at their interests while the NTs are out playing.
ALSO, I guess with all those that have such ralatively high IQs, there must be a lot that have really LOW IQs, and they don't qualify for an AS diagnosis.
ALSO, apparently the average aspie has a pretty strong long term memory.
So I guess it isn't that unexpected.