"The California Constitution properly must be interpreted to guarantee this basic civil right to all Californians, whether gay or heterosexual, and to same-sex couples as well as to opposite-sex couples."
Allowing gay and lesbian couples to marry "will not deprive opposite-sex couples of any rights and will not alter the legal framework of the institution of marriage."
Bilerico has some good posts on the subject (including one warning about the socio-political-legal backlash that will likely follow. So once you're done doing the happy dance, get your activist shoes out and get ready to politic, ok?).