Now that the Supreme Court has invalidated the Defense of Marriage Act and struck down California's Proposition 8, in effect granting federal recognition to same-sex marriages contracted in states where it is legal, the same-sex marriage "ball" will certainly continue to gain momentum. Justice Kennedy's ruling that "the federal statute is invalid, for no legitimate purpose overcomes the purpose and effect to disparage and injure those whom the State, by its marriage laws, sought to protect in personhood and dignity" in effect argues that refusing to respect legal marriages created by same-sex couples is a kind of discrimination that fails to respect the legal dignity of persons.
There can be no doubt that many U.S. bishops will not receive this decision warmly, and will argue further that this decision will negatively impact Catholic church institutions and agencies, which for the foreseeable future will not recognize these civil marriages for purposes of employment benefits; indeed there have been several high profile cases of same-sex partnered employees losing their jobs at Catholic high schools and parishes when their relationships or civil marriages came to light. There will likely be more political drama as states that already permit marriage-like institutions for same-sex couples are pressured through their own courts or legislatures to "upgrade" those institutions to give same-sex couples access to federal benefits.
I for one would hope for a kind of pause on the bishops' approach to this question: It should be obvious now that, on the civil side of things, same-sex couples have convinced Americans that they deserve access to the civil benefits of marriage. We in the church need to be having our own conversations about the religious institution of marriage and the religious meaning of human sexuality–long a monologue from the hierarchy that has not included the voices of lay people, married, single, gay, bisexual, or straight. Our own deliberations may lead us to new conclusions, or it may lead to a reaffirmation of old ones. But the signs of the times, today's rulings included, demand our common discernment.