And now for some good news:
It's only one poll, but it's clearly part of a multi-decade trend that's been moving in the right direction at the rate of a little over 1% a year. Until recently that is: in the past three years, polling on this question has improved at the rate of 3-4% a year. And this might end up being the greatest legacy of Vaughn Walker's decision in the Proposition 8 case. His opinion might not have much influence on the Supreme Court when they end up ruling on the issue, but it probably does have an impact on public opinion. People respond to the opinions of thought leaders and authority figures, and when judges and politicians start speaking out more openly about this, it makes it safer for ordinary citizens to follow suit. Some of that is probably what's happening here.
What's also remarkable — though not new — is the huge gender divide on this question: men are obviously far more threatened by the idea of same-sex marriage than women are. Being thought a sissy during childhood is a common and scarring experience for boys, but being thought a butch or a tomboy probably isn't such a wide or traumatizing experience for girls. In this particular case, men remain far more trapped in their traditional gender roles than women.