Oli,
I have experienced almost the exact same thing; my dd's development mirrors your child's. The difference is that I did not work with my child hardly at all in regards to academics. My husband would get down on the floor and do puzzle, letters, or numbers with her. He thought that he was responsable for her advanced developement. He has gradually come to realize that she is gifted in her own right and this has nothing to do with us. We do not help her on any of her school projects, essays, math, etc and she continues to excel.
Polly's comment-
"I don't really get why he isn't as wowed as me, in that holy cow amazement or simple appreciation of the unusual. I get that a lot, he doesn't. I'd love for him to say, "you'll never believe what DS did today".
I guess my theory here would be that men are gererally more vested in the workplace. Practical experience has told them that being highly intelligent does not guarantee success in the workplace. Studies have shown that EQ is more important than IQ. In fact, I think being super smart can result in someone not fitting in as well by virtue of their understanding things at a different level.
I try to keep my dd social. I find it much more challenging to do this than I think the parent of an average child would because dd is not at the same conversation level as her age peers. Of note is that in the real work, people are often promoted because their boss feels comfortable with them... this leads to trust. Studies have shown that people feel more comfortable with people who are similar to them.
I have taken a stance emphasizing that hard work and good manners (people skills) trumps intelligence while discussing abilities in our home. My husband seems comfortable with this stance.
Please excuse my over-anaylsis of the situation... I am a sociology major.