The Supreme Court of the United States has granted cert petitions in two same-sex marriage cases, Perry v. Hollingsworth (previously Perry v. Brown) and Windsor v. United States. Perry is the case challenging the constitutionality of Proposition 8 and Windsor is one of the cases challenging the constitutionality of DoMA.
In both cases, the Court appears to have granted the petitions on the merits and thus could decide the constitutionality of Proposition 8 and the constitutionality of DoMA. But the Court also added questions in each case about standing. In Perry the question is whether or not the supporters of Prop 8 had standing to pursue the appeals. If the Court were to decide that they did not, then it would not reach the merits. In that case, presumably either the 9th Circuit opinion or the District Court opinion would stand as the final decision on the matter. And since both Courts ruled that Proposition 8 was unconstitutional, that would be the end of the matter. In Windsor, the question is basically whether or not BLAG had standing. It is unclear at this time what the state of the law would be if the Court were to find that BLAG does not have standing. One would assume that Edie Windsor herself has standing to pursue her right to claim the marital deduction. And there is clearly an ongoing case or controversy since DoMA continues to be applied by governmental agencies despite the Justice Department’s failure to defend it.
For more details about these granted petitions and what they mean see Scotusblog here.