It will take a while to read through the details, but the short version is that a federal judge in Massachusetts found DOMA (well, specifically, Section 3 of DOMA) unconstitutional.
To further divide the class of married individuals into those with spouses of the same sex and those with spouses of the opposite sex is to create a distinction without meaning. And where, as here, “there is no reason to believe that the disadvantaged class is different, in relevant respects” from a similarly situated class, this court may conclude that it is only irrational prejudice that motivates the challenged classification.149 As irrational prejudice plainly never constitutes a legitimate government interest, this court must hold that Section 3 of DOMA as applied to Plaintiffs violates the equal protection principles embodied in the Fifth Amendment to the United States Constitution.
Both the Fifth and 14th Amendments are cited as being violated, which bodes well. However, the Tenth is cited as well, and that gives me pause. If states' rights to define marriage are being held as the major constitutional tenet being violated by DOMA, I am forced to (1) remember that I live in Arizona, and (2) conclude that my state's reaction will probably involve (a) passing a second, we-double-dog-mean-it marriage amendment, (b) criminalizing all non-procreative sex acts for people under 65, and possibly (c) seceding from the Union when the state legislature realizes suing the Feds to remove the 5th and 14th amendments from the Constitution ain't gonna fly, and it's the only way to avoid having to recognize the marriages of Tucsonans who might flock to Cedar Rapids for summer wedding junkets.
Another take on the potential Tenth Amendment can o' worms is at FireDogLake. Much reading to do!