The Supreme Court has decided not to hear any of the cases concerning same sex marriage. Several of the Courts of Appeals have held that it is unconstitutional for a state to refuse to marry same sex couples. All of these decisions are now final. At least in the states where those cases arose, and probably in the entire judicial circuits where those cases arose, states cannot refuse to allow same sex marriage and Social Security must recognize those same sex marriage as long as those involved stay in those states. In theory, the Supreme Court could decide at a later time to hear a new case arising from a Court of Appeals that has not yet acted on one of these cases. That seems unlikely at the moment but I would guess that Justices Scalia, Alito and Thomas would be happy to go down this route should a Republican be elected in 2016 and the composition of the Court changes.
The Attorney General can now say that the matter is resolved and that the Social Security Administration and other agencies must immediately recognize same sex marriages in every state. However, the Attorney General could study the matter for many months and then say that the issue must be legally resolved separately and tediously in each state or at least every judicial circuit until the Supreme Court has refused to hear a case from each state or at least each judicial circuit, a process that will take another year or more. I think the Attorney General should do the former but based on past action will probably do the latter.