NBC reports:

WASHINGTON – Lawyers for former Ambassador Joe Wilson and his wife, Valerie Plame, tell NBC they plan to file court papers Wednesday in their civil suit to include former State Department top official Richard Armitage as an additional defendant. It took three years for Armitage to publicly admit, last week, that he was the first to leak the identity of Valerie Plame Wilson to reporters.Melanie Sloan, an attorney for Citizens for Responsibility and Ethics, who are representing the Wilson’s, tells NBC that is was not okay for Armitage to leak Plame’s name to Washington Post reporter Bob Woodward and columnist Bob Novak.

The Wilsons’ lawsuit alleges a malicious conspiracy involving Cheney, Libby and Rove to “punish” Joe Wilson. But of accidentally leaking Plame’s identity, Armitage said, “I feel terrible,” and “I didn’t know the woman’s name was Plame. I didn’t know she was an operative.” Even Plame conspiracy-theorist Chris Matthews isn’t willing to go so far as to say that Armitage was in on the conpiracy — Matthews prefers to suggest that Libby et al duped Armitage into leaking. Are the Wilsons’ now claiming that Armitage was in on the plan to “punish” Wilson for criticizing a war that Armitage also opposed? Who outside the nutroots and Keith Olbermann is going to believe that?

UPDATE: Another differing recollection. Yet Scooter Libby is the only one on trial.