As I noted earlier today, the Second Circuit Court of Appeals ruled that the Defense of Marriage Act is unconstitutional. The Second Circuit covers New York, one of the several states where same sex marriage has been legalized. DOMA affects immigration cases in a variety of ways. A number of immigration benefits are tied to being legally married to a US citizen or permanent resident and DOMA bars the federal government from recognizing same sex marriages legally performed in the US or abroad.
The ruling is important, but it's the second appeals court ruling and until the US Supreme Court weighs in, USCIS is not likely to reverse course. The White House is no longer defending DOMA in court (the Republicans in Congress are), but it has also said it will continue to operate under DOMA until the courts have definitely ruled.