That brings me to my best guess of what did happen: Novak told Fitzgerald a story that helps his sources. It went something like this:

Yes, Mr. Fitzgerald, Bush Aide X and Bush Aide Y both told me that Valerie Plame worked at the CIA and that they suspected she had sent Joseph Wilson on his now-infamous trip to Niger where he determined it was highly unlikely that Iraq had been shopping there for uranium to be used in a nuclear weapons program. But neither one of these two fine Americans told me that she was an undercover operative at the CIA. If you will again look at what I wrote, I referred to her as an "Agency operative on weapons of mass destruction." I never reported she was in a secret position. In fact, the use of the word "operative"—which I suppose could connote a clandestine position but does not necessarily do so—was mine alone. These sources merely said to me she was employed at the CIA. As a newspaper columnist, I used the most evocative term I could think of at the time. I take full responsibility for that.

And to make everything neat and tidy, Bush Aide X and Bush Aide Y each essentially said the same thing to Fitzgerald:

I heard hallway chatter that Valerie Plame was at the CIA and that she had something to do with Wilson's trip to Niger. I passed this on to Novak and Time magazine. I was never aware that she was working undercover or that by sharing this gossip I would be disclosing confidential information that identified a covert official. After all, as you know, Mr. Fitzgerald, not every CIA employee is a clandestine official.

Voila. No crime. A thuggish act of political retribution that destroyed a CIA officer's career and undermined national security, yes. But no crime.