1> We know that Cheney was over at CIA headquarters a lot during the run-up to the war, and was, according to reports, leaning on the agency to fix the intelligence, just as the Downing Street Memos suggest.
2> We also know that the Bush administration created the Office of Special Plans at the DoD to essentially bypass the CIA and provide and package the evidence needed to justify the war.
3> We know that the DoD got rid of the Office of Special Plans once the war was justified, as it was considered controversial and unnecessary.
4> We know that the Bush administration blamed the CIA for the faulty intelligence that led to the war, even though several prominent members of the CIA were on record denying this took place.
5> We now know that the CIA under Porter Goss no longer has direct access to the president, and that the Pentagon has taken over much of the country's intelligence capacity.
In other words, the attack on Wilson was not intended to out his wife at all -- the White House would've never willingly brought that upon themselves. It was to discredit Wilson's claims of the White House misleading the public by citing a counterfeit document, alleging Iraq's attempt to buy Nigerian "yellowcake" uranium. Valerie Plame, a CIA operative, actually recruited and paid her own husband to go over to Nigeria and investigate the "yellowcake" claims... which makes it sound like she had an agenda against the Bush administration. There was no way for the Bush administration to point out this fact, however, without mentioning that Valerie Plame was a CIA operative. It is doubtful, however, that it ever crossed their mind that by saying this, they committed a federal crime.
At the time, the Bush administration were riding high on success, and laughing at the CIA's "partisan", "worrywart" mentality. It was only afterwards that they suggested that the CIA were the ones actually responsible for buying into the bad intelligence, primarily provided by Ahmed Chalabi's Iraqi National Council.
If you need a good idea as to what people were actually taken in by Chalabi and his phony information, all you have to do is look at who his best friends were within the Bush administration. It certainly wasn't anyone over at the CIA.
In March, 1995, Chalabi attempted to stage a coup against Saddam Hussein with CIA backing, but in order to persuade the Iranians that he had the CIA's backing, and that they should support him too, Chalabi "accidentally" left a counterfeit memo on his desk for Iranian diplomats to read, outlining a CIA-approved attempt to assassinate Saddam Hussein. This information was sent by the Iranian diplomats to their government and then intercepted by the CIA, who, thinking their man in the Middle East had gone rogue and that news of the coup was leaked, promptly scrubbed their support for the revolt and cut off all funding for the INC. It was also the CIA under Tenet who accused Chalabi of being an Iranian spy, which nearly led to his arrest. Clearly, prior to the invasion of Iraq, the CIA wouldn't have considered Chalabi as particularly credible, and there was no love lost there. It was the DoD, not the CIA, that tried to appoint Chalabi as ruler of Iraq.
So, who did buy into the phony evidence of Chalabi and his Iraqi National Congress? Most likely, it was Richard Perle and Paul Wolfowitz. Perle and Wolfowitz both had close ties with Chalabi dating back to their involvement in PNAC, where they signed off on a policy paper advocating the overthrow of Iraq. Together, the two of them greatly influenced U.S. defence policy, influencing Rumsfeld, Feith, and other prominent Republicans. After 9/11, Wolfowitz and Rumsfeld approached Bush, advocating that a military invasion of Iraq should be part of the goal of the War on Terror. This led directly to the creation of the Office of Special Plans, which the DoD used to fix the evidence, bypassing the CIA and going straight to the top.
So, basically, it's not about someone in the White House leaking a CIA agent's identity. It's about perjury, the obstruction of justice, lies to create a war, and the falsification of testimony and evidence that may have caused irreparable harm to the world's greatest intelligence service.