Barack Obama just (finally) said that same-sex couples should have the same legal right to marry as heterosexual ones. Obviously just because he says it doesn't mean it's going to happen. But it's worth noting that if we did grant equal marriage rights tomorrow it would likely give the economy a powerful shot in the arm. Weddings are expensive, so a sudden change in the legal framework would be a shock to economy-wide aggregate spending as a whole bunch of long-standing committed same sex couples rushed to celebrate with friends and family.
Of course it's possible the Fed would simply nip things in the bud and kill the party.