The Social Security Administration has started payments on some retirement spouse claims for same-sex couples, according to an announcement by Carolyn W. Colvin, the acting commissioner of Social Security. 

Here's her statement, via Buzzfeed

I am pleased to announce that Social Security is now processing some retirement spouse claims for same-sex couples and paying benefits where they are due. We continue to work closely with the Department of Justice. In the coming weeks and months, we will develop and implement additional policy and processing instructions. We appreciate the public’s patience as we work through the legal issues to ensure that our policy is legally sound and clear...I encourage individuals who believe they may be eligible for Social Security benefits to apply now, to protect against the loss of any potential benefits. We will process claims as soon as additional instructions become finalized.”

Social Security now joins some other federal agencies in beginning to implement changes on spousal benefits in the wake of the Supreme Court ruling on the Defense of Marriage Act. Days after that ruling, the White House sent a memo to executive agencies clarifying that the federal government would now offer equal benefits to married, same-sex partners of federal employees. As Buzzfeed cautions, however, it's not clear how widely the Social Security benefits will apply, as a host of legal issues are still presumably being resolved: 

It was not immediately clear what retirement claims are being covered and what eligibility criteria were being used to determine who would be eligible for such benefits. Specifically, it is not yet clear whether same-sex couples married where such couples can legally marry but who live in a state that does not recognize such marriages would be eligible.

Meanwhile, there's been progress on a couple of other benefits fronts, too, for instance:

Veterans' benefits: The Republican-controlled House of Representatives announced in July that they would no longer defend a provision in U.S. code that limits spousal benefits for military veteran couples to those comprised of one man and one woman. The decision pertains to two lawsuits challenging that provision, which the DOJ had previously declined to defend

Green cards: two days after the law was struck down,  Bulgarian Traian Popov became the first person to receive a green card through a same-sex marriage. The Department of Homeland Security quickly confirmed that married, same-sex couples were now eligible for green cards, just like any married couple with one partner going through the immigration process.