|Fitch||Moody's||Standard and Poor's|
Californian bond ratings from Bloomberg. Greek bond ratings from Reuters.
Wikipedia has a color coded chart of bond ratings at http://en.wikipedia.org/wiki/Investment_grade
Both California and Greece suffer from serious fiscal dysfunction in their own different ways. Both of them are now playing games of chicken with their respective federal authorities, the United States and the European Union.
Greece, I think, has a stronger position with regard to the authorities in Brussels and Frankfurt than California does to Washington. Also, the Greeks are much better at this kind of thing than the Californians, having managed to get themselves into the eurozone in the first place by cooking the books. And they have centuries of practice in driving a sharp bargain.
On the other hand, economically California is a much more important part of the United States than Greece is part of the European Union.
It's going to be interesting to see who blinks first.