Thanks indigo and puffin for your insights. I've got to say this is really depressing.

There are approximately 80,000 school-aged kids in San Francisco. If we assume that the top 2% are gifted (IQ > 130) then there should be about 1,600 gifted kids here. That's ~125 gifted kids per grade level in a city of less than 47 square miles!!! (Most likely the numbers are even higher because high IQs are over-represented in SF). So, where are all these smart kids? Where do they all go? Within the city there is not a single school, public or private, that offers gifted education. Evidently there is a market for it, so why is no private school jumping in? Is gifted education really that hard? Are we too egalitarian? What's the core of the problem?

I am sure this has been discussed many times, but I am new to this and I still have not accepted the bleak reality of GT education...