In the adjudications context: The USCIS has provided internal guidance that filings based on same-sex marriages are to be held in abeyance rather than rejected pending the outcome of the DOMA activity. What that means is that even if the I-485 isn’t adjudicated right away it’s possible to get employment authorization and proof of the right to be in the United States while the issues are worked out.
In the removal context: Manhattan Immigration Judge, Terry A. Bain, and the DHS trial attorney agreed to halt the removal of Monica Alcota, who was married to Cristina Ojeda, a US citizen, Connecticut in 2010, based on the argument that their same-sex marriage should be recognized for the purposes of immigration benefits.
Recently the Obama administration decided that it will no longer defend the Defense of Marriage Act in court. The Defense of Marriage Act states that federal policy is that marriage is between one man and one woman. Therefore, despite a general USCIS policy that states that marriages which are valid in the jurisdiction in which they took place, same-sex marriages are not recognized even if they’re legal where they took place.
All of that could change if the US Supreme Court rules that the DOMA is unconstitutional, which is likely as the government will no longer be defending the law. Should that happen, or should it be repealed, same-sex marriages should be recognized by the USCIS for the purposes of family based petitions.