It seems as though she wasn't, but isn't it more complex than that?
My understanding is that, by outing Plame, they also outed a business that was a CIA front (Brewster-Jennings and Assoc). Wouldn't that also lead to other covert ops being outed, even if by no other means than by foreign intel agencies who we know are watching this thing closely.
In fact, isn't it possible that outing her in this manner could jeopardize the safety of her contacts, who are covert? I know if I'm a foreign gov't, I'm re-creating her activities in my country to determine who she interacted with because I wanna' nail me some spies.
That is, IMO, outing covert operatives. Whether it's against the law as the law is written, I dunno'.
On a related note, I hear Fitzgerald isn't going to issue a final report on his investigation. I guess that means one of two things, either we'll never know any of the results of his findings, or indictments are on the way...