That move comes with asterisks:
According to the New York Times, "While he will announce a list of benefits, officials said, they are not expected to include broad health insurance coverage, which could require legislation to achieve" because of (you-guessed-it) the Defense of Marriage Act (DOMA).[sigh]
Also in that article, "...administration officials said the timing of the announcement was intended to help contain the growing furor among gay rights groups. Several gay donors withdrew their sponsorship of a Democratic National Committee fund-raising event next week, where Vice President Joseph R. Biden Jr. is scheduled to speak."
And what's the furor about? Obama's DOJ choosing not only to defend DOMA, but to defend it using some of the right wings' most disgusting and shameful talking points such as comparing same-sex marriage to incest. The New York Times in a Monday editorial called it a "A Bad Call on Gay Rights" and quoted Joe Solmonese, president of the Human Rights Campaign, who said, “I cannot overstate the pain that we feel as human beings and as families when we read an argument, presented in federal court, implying that our own marriages have no more constitutional standing than incestuous ones.”
The Times also adds that, "There is a strong presumption that the Justice Department will defend federal laws, but it is not an inviolable rule."
I will add that Obama's DOJ has, for example, not prosecuted Bush/Cheney on torture or any other broken treaties and war crimes.