Armitage was the leaker?

According to CNN, former Deputy Secretary of State Richard Armitage was Bob Novak's original source for the identity of Valerie Plame. [CNN] Armitage - Colin Powell's close friend and right-hand man, who resigned shortly after Powell did in 2005 - was never closely aligned with the Cheney/Rove crowd, and it is extremely hard to imagine him cooperating in some kind of plot to out Plame in retaliation for her husband's criticisms of the administration's WMD claims. Instead, Armitage apparently leaked her identity accidentally:

The Armitage connection to the Novak column is also outlined in a new book, titled "Hubris," by Michael Isikoff and David Korn.

In the book, Armitage is quoted as telling former Assistant Secretary of State Carl Ford that "I'm afraid I may be the guy that caused this whole thing." [CNN]

The Intelligence Identities Protection Act only applies to intentional leaks of a covert agent's identity, and Patrick Fitzgerald, special counsel in the leak investigation, has said that he will not prosecute Armitage.

"Sources: State Department Official source of Plame leak" [CNN]
"The Wilson-Plame-Novak-Rove Blame Game" [FactCheck.org]