Jim Lindgren thinks Rove should be fired, and that if he isn't Bush is violating his promise to deal with anyone who leaked the information. I have to disagree with that.
The most likely explanation is that Rove is Cooper's source, but not the leaker. Rove probably heard about Plame from a reporter, and merely passed the information on to Cooper, another reporter, in making the case that Wilson was lying (which was later confirmed by the Senate report). He should not even have had access to the original information based on his position at the time. Note Rove's phrasing regarding Wilson's wife using the caveat "apparently." That, too, suggests second-hand information.
That is why Bush has not fired him, and will not: passing information gleaned from one reporter on to another reporter is not "leaking." Yesterday on TV, Bush looked almost smug in telling reporters he was confident in Rove; he had a little "I know something you don't" twinkle in his eye. The admin clearly believes they will be vindicated when all the facts come out.
It follows that Judith Miller may actually have received the original information from her source, probably an adminstration-friendly source in the CIA, which is why as an investigative journalist she will go to jail to protect that source. If she doesn't, her career is over; you can't burn a source like that and expect anyone to trust you in the future.
UPDATE: It's also been acknowledged by several reporters that Plame's identity wasn't much of a secret. For Rove not to know what was common knowledge in the press corps would be unusual.
Also, in Novak's follow-up column, he appears to indicate he didn't even know Plame's identity was supposed to be secret. That's pretty indicative that Rove could have (should have, in fact) known her identity from media sources, and committed no wrongdoing whatsoever by passing the information along.
So what do we have now? We have no one charged with any crime, yet, so presumably the person with access to the CIA documents has not been identified. We have Robert Novak, who has probably talked about who his source was, as he is not sitting in jail. That, and the fact Miller is still looking at prison bars, makes it somewhat likely his source is another media type (perhaps even Miller) and not the original source. So, my hypothesis is this: Judith Miller is the original source of the information that Wilson's CIA wife recommended him for the Niger job. She told Novak and Rove, or (more likely) told someone who told them.
Of course, I could be wrong. There's lots of other possibilities. But I think this fits what we know and what we can infer from the behavior of the principals involved.