Excellent premise and I loved the ending! Made me wish for more (a series!) to continue on in what happens as this society evolves and hits it's own growing pains. But then, SimCity was always my favorite computer game (geeky, I know! =)
There is a lot of waxing poetic and descriptions of the differences in the 'other' California, which I couldn't get into. I've not spent much time in California, so I didn't recognize most of the place names. If you've been there much (or live there now), you'll undoubtedly get more of a buzz from it.
Otherwise, a fully excellent book!