According to this posting on The Volokh Conspiracy site referencing this article on BuzzFeed regarding how the Social Security Administration (SSA) plans to handle spousal benefits in the wake of the Supreme Court’s Defense of Marriage Act ruling:
the SSA has bucked the trend in other executive agencies of paying benefits to all couples whose marriage was validly celebrated. Instead, the SSA will pay benefits only to a couple whose home state (“domicile”) recognizes their marriage. …
SSA’s decision may well be required by 416(h)(1)(A)(i), and if so it is hard to criticize the administration. But the decision has the unfortunate effect of ensuring that same-sex couples will be married for some federal purposes and not for others.
Left uncertain, according to Volokh’s Will Baude, is whether same-sex couples in domestic partnership states such as New Jersey will be entitled to SSA spousal benefits.
Nevertheless, it’s pretty clear that in a post-DOMA world the federal benefits disparity between states that recognize same-sex marriage and those that don’t is going to make living in a marriage equality state, when practical, much more appealing to gay couples. And those who must remain in non-equal states due to career requirements or the need to care for elderly parents, for instance, will suffer the financial impact—unless and until state laws are changed or the courts rule otherwise.