The Supreme Court recently held that the Defense of Marriage Act (section 3) is unconstitutional. In so doing, they took away the only thing standing between same-sex married couples and immigration benefits. Almost immediately after the decision, the Department of Homeland Security, US CIS, and the Department of State all indicated that they would begin considering family-based immigration petitions for same-sex married couples provided that their marriages were valid in the location where celebrated. That means that if a couple in Missouri went to get married in Iowa, then return to reside in Missouri (a state with a very specific ban on same-sex marriage) they would still be considered married for immigration purposes.
In fact, the Director of US CIS, Alejandro Mayorkas, stated at the AILA annual convention in San Francisco that they had in fact kept track of all denied petitions dating back to February 2011 (when the President announced his administration would no longer defend DOMA), and they would take action on them soon - leading us to believe US CIS would reopen them on their own.
The first green card approved was for a couple in Florida who were married in New York. Because their case was still pending at the time DOMA was struck down, they did not need to wait to get a petition on file, and did not have to have it reopened.
We are now days away from filing our first case for a same-sex married couple and could not be more excited for them. One thing to keep in mind is that married couples have to prove that their marriages are bona fide, which for couples in states which do not recognize their marriage, this can be tricky. Being creative with evidence to establish the bona fides of the marriage is important, and something we take great pride in.