Though I am personally opposed to homosexuals marrying, I am in complete agreement with the ruling and reasoning offered by the California court. I have said on many occasions that the ban on homosexual marriage runs afoul the "equal protection" clause because the state gives married couples benefits that is does not give to single people. Curiously, the situation with "civil partnerships or whatever they are being called, runs afoul the same logic that undergirded the concept of separate but equal. This was well explained in the ruling as well. It's pretty odd that those opposed to homosexual marriage failed to see that they were on the losing side of the argument.
My position has been and continues to be that the state ought to get out of the marriage business altogether. Instead I have proposed that all "marriages" be civil unions in the eyes of the state. The act of Marrying ought to be left to religious organizations who would be free to marry or not marry who they want given that the state cannot dictate to religious institutions what their ideologies are, nor whom they can or cannot discriminate.
However; what is more important about this decision is that the reasoning also makes any laws against polygamy in California unconstitutional. There is no leap of logic that would justify the marriage of two men or two women and not allow the marriage of three, four or more individuals. In the absence of the legal standing of marriage as a necessary social construct to produce and raise children, there is then no legal standing to prevent a man and any number of women (of legal age of course) from doing the same. The "2" designation is simply an arbitrary limitation imposed by the state and the state has no rational or legal reason to enforce such an arbitrary limit if that same state can allow for two men or two women to marry. Mind you that unlike homosexual relations, polygamous relations can produce children in no different manner than any other heterosexual union and is therefore far more "natural" than any homosexual union.
Furthermore, on the matter of child rearing, it is far more beneficial to both child and parent when there are more adults to provide both supervision and finances. In terms of pressures on family members, there is "ideally" more help around and more opportunities for women in polygamous relationships since any number of persons are available as babysitters, etc possibly negating the need to expensive childcare.
I find it odd and insightful that a good number of homosexuals, while fighting for their "right" to marry, will in the next breath talk all manner of trash about polygamy, some even going so far as to point to the recent raids in Texas. The truth of the matter is that the issue in Texas (and possibly elsewhere) is one of child abuse, not plural marriage. Child abuse happens in "broken" homes, two parent homes, among extended family members, etc.
I think the constitutional issues coming out of this will be huge. Utah was admitted into the union on the basis of it banning polygamy. Seeing that the argument about 'state interest' has been shot down in two states, for maintaining marriage as between one man and one woman, I think the LDS church will soon be in a position to sue not only the state of Utah but the Federal Government over this issue. Since "family" is being defined in terms of who loves who and who can raise children (as opposed to producing them), there is no legal standing to ban polygamy.