Yes, the California supreme court has overturned a state ban on gay marriages.
But note the dissenting opinions. For example:
"In a dissenting opinion, Justice Marvin Baxter agreed with many arguments of the majority but said the court overstepped its authority. Changes to marriage laws should be decided by the voters, Baxter wrote."
Gosh. Marriage laws decided by the voters; not by a court acting as a legislature.
That's an important fundamental that conservatives should stress concerning this ruling.