Plame: Who outed Who?

Cliff May, while commenting on this piece by Byron York, wonders aloud the thing that some others have likewise wondered but that no one seems willing to take head-on:

So I ask again: If Armitage and Novak did not believe Plame was (or had formerly been) undercover, where did that idea come from? The answer: It was first raised in a story by the Nation’s David Corn. And the only source named in that story is Joe Wilson, who had a close relation with Corn and with the Nation.

Does this suggest it was really Wilson who exposed his wife’s covert status and did so, in league with Corn, as a way to damage the White House? If there’s a more logical or likely interpretation of the facts as we now know then, I haven’t heard it.