Take a look at what the market thinks of the chances for a California default.
http://www.economist.com/blogs/dailychart/2010/11/credit-def...
As of a week ago, "The state with the biggest budget problems, California, is seen as slightly less likely to default than Spain but slightly more so than Italy."
Note that Spain is a total mess with an unemployment rate around 20%.
It's hard to default when your can print your own currency. I think the California bond holders will never take a haircut. The US will just print more dollars.