So now we know. The man behind the leak of former CIA operative Valerie Plame's identity was not presidential adviser Karl Rove, nor Vice President Dick Cheney's former chief of staff, I. Lewis "Scooter" Libby, who is under indictment for allegedly obstructing the investigation into the leak and lying to investigators. It turns out the leaker was former State Department deputy secretary Richard Armitage, a man much loved by the media precisely because he could always be counted on to tell tales out of school. In his own words, Armitage is "a terrible gossip," an admission he made during the Iran-Contra congressional hearings in 1987. The credit for unearthing this information goes to David Corn and Michael Isikoff in their forthcoming book, "Hubris: The Inside Story of Spin, Scandal and the Selling of the Iraq War."

Corn's role is noteworthy because he is the Washington editor of the left-wing magazine The Nation and an outspoken critic of the Bush administration. What's more, he did much to transform the Plame incident into the national scandal it became. Corn admits that he was the first reporter to float the idea that whoever revealed Plame's name to syndicated columnist Robert Novak, who then published it in a 2003 column, may have violated the Intelligence Identities Protection Act. The law prohibits government officials from revealing the identity of covert officers, provided the official knew that the person was covert and obtained the information through his official duties. And since Novak cited "two senior administration officials" as his sources in the article, Democrats in Congress began clamoring for a full-scale investigation, which ultimately led to the appointment of Patrick Fitzgerald as a special counsel and the indictment of Scooter Libby in October 2005.

Corn deserves recognition for reporting what turns out to be an inconvenient fact. It can't please him that the investigative trail in the Plame leak led not to hardliners in the West Wing but to a high-placed dove in Foggy Bottom. But I'm not ready to take my hat off to Corn just yet. His new revelations really beg out for a mea culpa for having got it wrong in the first place when he alleged, shortly after the leak, that "there is evidence Bushies used classified information and put the nation's counter-proliferation efforts at risk merely to settle a score." Yet, Corn has decided to use the publication of the exculpatory information to reassert, once again, his attacks on the Bush White House.

Corn implies that it doesn't matter who the original source of the leak was because Rove confirmed Plame's identity when asked about it by Novak and passed on the information to Matt Cooper of Time magazine. Corn also blames Libby for revealing Plame's identity to another reporter, Judith Miller, then a writer for the New York Times. But neither Cooper nor Miller disclosed the information; and it was Novak's column that spurred the federal investigation that later resulted in Libby's indictment. And Armitage was Novak's primary source.

Corn admits that Armitage was "a war skeptic not bent on revenge" against Plame's husband, former Ambassador Joseph Wilson, for publishing a 2003 article critical of administration claims that Iraq was trying to secure materials used in building nuclear weapons. But instead of acknowledging that Armitage's role in the leak undermines the whole conspiracy theory that the White House would stop at nothing -- even jeopardizing national security -- to get even with its foes, Corn says the Plame affair "remains a story of ugly and unethical politics, stonewalling, and lies."

The real ugliness -- indeed, cowardice -- is that the original culprit who leaked Plame's name never came forward publicly to explain himself. Although Armitage did reveal to federal prosecutors that he gave Plame's name to Novak, he did so only when he may have worried that he could become the target of the investigation after Novak noted in a column, three months after the original story, that his source was "no partisan gunslinger." Nonetheless, Armitage let sharks in the press circle the West Wing looking for blood for the next two and a half years, knowing he was the real blabbermouth.

Worse yet, Scooter Libby now faces possible jail time for allegedly misleading statements in an investigation into a non-crime committed by someone else, a person, in any event, who was already known to federal prosecutors. The real crime here appears to be this malicious prosecution.