I'm absorbing the statement, which you can read here. My thoughts soon. Meanwhile, Jim Burroway:

DOMA is still on the books, and it has not been declared unconstitutional. It does mean however that the Justice Department won’t defend section 3 of the statute which bars federal recognition of marriage of same-sex couples when that portion of the law is challenged in court. And so one possibility is that we may have a national patchwork of DOMA enforcement it is kaput where Federal judges or their Appeals Courts have ruled against it, while it remains on the books where the courts have upheld the law or haven’t ruled. 

That would make, for example, the IRS’s administering the tax code a logistical nightmare, with some gay couples filing as married couples in some jurisdictions while others are barred from doing so elsewhere. Immigration can become a similar quagmire for transnational couples. Without, ultimately, either an appeal somewhere to the Supreme Court or repeal of DOMA itself, it’s going to be very intresting and probably frustrating for a very long time.

Dale Carpenter:

There are many questions to ponder, including: who will now defend DOMA and will they have standing to do so?  The DOJ suggests that members of Congress may be able to defend the federal law, but that is far from clear under the Court’s standing precedents, like Raines v. Byrd, written by Chief Justice Rehnquist. 

Elsewhere Carpenter asks whether the president now supports marriage equality. Adam Serwer:

Both of Holder's statements carefully state that they will cease to defend Section 3, without commenting on the constitutionality of the rest of the law. Section 2 still allows the states not to recognize same-sex marriages performed in other jurisdictions. But that doesn't mean that the administration necessarily believes Section 2 is constitutional. 

Jack Balkin:

Under these conditions, it becomes much more likely that DOMA will be struck down by at least one federal Court of Appeals-- possibly the Second Circuit, where the latest cases are being brought--and therefore even more likely that DOMA will be struck down when it finally gets to the Supreme Court. All of my previous predictions as to how constitutional challenges to DOMA will go forward must be revised.

(Photo: Aleyna Stroud (L) and Mandy Harris kiss after requesting and being rejected for a marriage license at the County Clerk's Office in Los Angeles on Valentine's Day, February 14, 2011. By Robyn Beck/AFP/Getty Images)