Maggie and Brian, as well as Matt Staver of Liberty Council, are quoted in this article from LifeSiteNews:

Matt Staver of Liberty Counsel called the decision “outrageous and unthinkable” and added that the president has “betrayed the American people by his refusal to defend the federal law that affirms what many courts upheld as constitutional, namely, that marriage is between one man and one woman.”

Brian Brown, President of the National Organization for Marriage (NOM) said in response, “we have not yet begun to fight for marriage.”

“The Democrats are responding to their election loss with a series of extraordinary, extra-constitutional end runs around democracy, whether it’s fleeing the state in Wisconsin and Indiana to prevent a vote, or unilaterally declaring homosexuals a protected class under our Constitution, as President Obama just did,” Brown said in a press release. “We call on the House to intervene to protect DOMA, and to tell the Obama administration they have to respect the limits on their power. This fight is not over, it has only begun!”

However, NOM chairman Maggie Gallagher says she sees a benefit to the pro-marriage movement in the decision.

“The Obama administration was throwing this case in court anyway,” she said. “The good news is this now clears the way for the House to intervene and to get lawyers in the court room who actually want to defend the law, and not please their powerful political special interest.” [source]