USCIS just issued a Questions and Answers following SCOTUS' ruling that DOMA was unconstitutional. USCIS says that same-sex married couples may file a Form I-130 to petition for a spouse and can no longer be automatically denied as a result of the same-sex nature of the marriage.
If the couple was married in a U.S. state that recognizes same-sex marriage, or in a foreign jurisdiction that allows it, even though they are living in a state that does not recognizes same-sex marriage the couple can still file the petition. In evaluating the petition, as a general matter, USCIS looks to
the law of the place where the marriage took place when determining whether it is valid for
immigration law purposes.