My memory tells me that she or her hubby had openly stated that she worked for the CIA and that it was common knowledge before the incident. I don't remember any proof of her clandestine status.
Thanks for asking this question!
In the Hannity & Colmes interview linked below, Valerie Plame’s CIA supervisor blows left-wing witch hunt “Fair Game” framing that Scooter and Cheney exposed Plame’s covert status. At the time Plame only had “light non-official cover” (trivial compared to covert status) as a person who had the appearance of being only an “overt” CIA employee, which was the appearance that Libby and Cheney relied on when they sought to link her to the inaapropriate selection of her husband to go to Niger.
http://www.foxnews.com/story/0,2933,162811,00.html
COLMES: Also, the fact that her cover was blown — doesn’t this expose every asset? Doesn’t it expose other people, every operation that she might have been involved with, and possibly put lives at risk?
RUSTMANN: No, I don’t think so. I think she had official cover for the first part of her career, when she was overseas in an official capacity. She came back to headquarters for a while, and then they sent her out on a light non-official cover.
She was out there. She was collecting information under that cover. She came back to headquarters. They probably then reverted her back to her official cover. In other words, so she wouldn’t — her W-2’s would not say...
(CROSSTALK)
COLMES: So she went back into cover. But for example, didn’t they expose a front operation that she helped run, Brewster-Jennings & Associates, this made-up company. And wasn’t that exposed as a result of all this, and can’t this damage intelligence operations and our security?
RUSTMANN: Well, actually, no, because it isn’t a big deal. It was a light non-official cover. There was, you know, a phone. There was very little backstopping to that company. It wasn’t like she was working for a major multi-national American company or foreign company where there could be some severe blowback if that were to come to...
COLMES: Are you saying there are no repercussions of this? There’s no repercussions of her having been exposed as a covert CIA agent, even though she was non-covert at one point?
RUSTMANN: There are no major repercussions to the cover mechanism, no. To her — the question again gets down to whether somebody did this with malice or forethought. Then it’s a crime, and that person goes to jail.
COLMES: But isn’t the question whether any damage was done because of the revelation? Whether lives were harmed, whether anyone was harmed, or security was harmed?
RUSTMANN: Yes, I don’t think so. I think, if she were out there in that capacity, in that non-official capacity, and if she was handling agents — she was handling agents in another alias — we have different layers of cover that work.