Finally -- I was almost convinced they were going to keep punting the marriage cases down the line as long as they could. From NYT:
The Supreme Court announced on Friday that it would enter the national debate over same-sex marriage, agreeing to hear a pair of cases challenging state and federal laws that define marriage to include only unions of a man and a woman.
One of the cases, from California, could establish or reject a constitutional right to same-sex marriage. Another case, from New York, challenges a federal law that requires the federal government to deny benefits to gay and lesbian couples married in states that allow such unions.
The cases are Hollingsworth v. Perry (formerly Perry v. Brown, the Prop 8 case) and United States v. Windsor (DOMA).
Ari Ezra Waldman, as usual, has a good clear analysis of the decision to take these cases at Towleroad; you might also take a look at this report, which includes some fairly entertaining reactions.