The Supremes overturned California Prop 8 which forbids gay marriage in the state of California. They did it on a technicality rather that come right out and say "The US Constitution Article such-an-such means gay marriage is legal". Probably they couldn't agree among then selves on such an interpretation. Instead they decided that the plaintiffs lacked "standing", a lawyer's way of throwing out lawsuits. And doing it this way, the ruling only affects California, it doesn't impose gay marriage on the non-gay marriage states, which would cause political outrage.
It also supports judge made law. It was a lower court that overturned Prop 8. That ruling is what got appealed all the way to the Supremes. The Supremes have said, "Doesn't matter what the voters say, we judges can make our own laws to suit ourselves." Real democracy that is.
On the real issue, I'm neutral, we have gay marriage here in New Hampshire, the legislature voted it in. There has been some grumbling, but the bulk of the citizens are going along with a state law passed by majority vote in the state legislature. The sky has not fallen.
While they were at it, in a separate case, the Supremes overturned most of the federal Defense of Marriage Act (DOMA) Here at least, they ruled that DOMA violated the equal protection clause of the Constitution. They didn't mention that DOMA was as hard on lesbians as it was on gays. Far as I am concerned, that's equal protection, or at least equal prosecution.
But heh, they are the Supremes and we are stuck with 'em.