It important to note that this is a federal district court decision. To become law it would have to survive the inevitable appeal to the federal circuit court level and then, if it made it there, get through the Supreme Court, which under present management seems hard to imagine.
Late Update: Here's a more detailed explanation of the case, sent along by TPM Reader CA. I'd recommend reading the piece. But the gist seems to be that the judge ruled against the part of DOMA which deals with the federal government's non-obligation to recognize state gay marriages. The court found that that part of the law didn't meet muster under the 14th and 10th amendments. So both equal protection but also the state's ability to define marriage. There were actually two separate cases Judge Tauro ruled on.