A friend has pointed out a pitfall for copy editors in the debate over same-sex marriages.
Careful writers, and editors, will avoid calling this "gay marriage." Gay people can get married now, just not to people of the same sex. And it happens more often than straight people may think.
On the same note, don't call what's legal now "heterosexual marriage." In addition to the gay people who could be married to someone of the opposite sex, there are bisexuals who are married as well.
Just say what you mean, "same-sex marriage," and it will mean what you say.
Now, will "gay marriage" work in a pinch for a tough headline? Probably. Having an important key word will help the headline more than hurt. But be cognizant of this term's shortcomings.