Ian Tuttle of National Review Online gives one of the most thorough explanations to date about what we know about the IRS leaking NOM's confidential tax returns:

"...[An] investigation could help to determine whether the impetus for the leaks came from within the IRS or from elsewhere. Eastman notes that one month before the leak, Joe Solmonese, HRC’s outgoing president, was tapped by the Obama reelection campaign to fill one of 35 national co-chair positions. “Then all of a sudden,” Eastman told Cavuto, “magically, our donor list shows up on their [HRC’s] website.” For NOM, then, “the central question is, did the IRS do it on their own, or was this part of a broader effort with campaign involvement?” It was very likely a coincidence — but an investigation is what NOM needs, and an investigation is what seems not to be happening.

... many defenders of traditional marriage refuse to be cowed by attempts to shame or intimidate them. After its donor lists were leaked last year, NOM set up Keep the Republic and Marriage, a website that encourages donors to give to NOM and publicly state their support for traditional marriage. The list currently has more than 1,400 names.

...At the June 4 Ways and Means hearing, Washington congressman Jim McDermott sneered that “Republicans are looking for a conspiracy where there isn’t one.” Connect the dots, congressman. It’s not paranoia when they’re really out to get you."