The first poll on the issue since the Massachusetts Supreme Judicial court ruling shows 65% opposed to same-sex marriage and 25% supporting it. Meanwhile, an article in the New York Times examines complex attitudes toward marriage among gays. The more I follow the debate, the clearer it is that, as Jacob Sullum has written, at issue is the perception that by legalizing same-sex marriage the state will be "endorsing" same-sex relationships. Maggie Gallagher in The Weekly Standard and Steve Miller in his Culture Watch blog at the Independent Gay Forum agree that the distinction between marriage and civil unions matters because, in Miller's words, "marriage confers dignity upon a relationship and civil unions don't." The Times article notes that "some [gay] couples said they would marry largely for symbolic reasons"—in the words of one man, "to say that we're just as normal as everyone else." Meanwhile, since the Massachusetts marriage ruling, I have heard several people who have been generally supportive of gay rights (including civil unions) gripe about being "forced to accept that it's completely normal" to be gay.
I suspect that legalized same-sex marriage, even if it were to become the law in all 50 states, won't have the impact that one side wants and the other fears. Social acceptance can only come from people, not government; just because something is legal doesn't mean people will be more likely to approve of it. There is evidence, for instance, that cultural attitudes toward abortion have become more negative since Roe v. Wade. The same Times article hints at the fact that legalization does not always equal acceptance: one man said that he would not marry his long-time partner because his conservative family would disapprove, despite being supportive of his relationship: "One year for Christmas they gave us bath towels with his initials and my initials. But a wedding would push them over the edge."
Privatizing marriage, as Sullum suggests and as libertarians like David Boaz have been arguing for years, would seem to be the most bloodless solution—now endorsed even by mainstream liberals like Michael Kinsley, whose column on the subject was provocatively titled "Abolish Marriage." Of course, that's about as likely as Jerry Falwell officiating at a gay wedding.