Based on the state statute that defines marriage as the union between a man and a woman, the Supreme Court of California, in a 5-2 vote, has declared all same-sex marriages issued in San Francisco, and elsewhere in the state, null and void.
On the bright side, the court did say that it was not considering the actual constitutionality of the marriage provision. Once the constitutionality appeal is heard (which is on the way), there is a chance that same-sex marriages may be re-instated.