Social Security death benefits go to surviving members of married opposite-sex couples, but not to same-sex couple survivors — even if they’re married in a state that recognizes their marriage — because of DOMA.
The same is true under any pension plan covered by the federal ERISA law, at least if the pension goes to the spouse. (But an employer may be able to set up a pension plan to enable you to leave your pension to your partner if you expressly so designate him or her.)