Interesting from a Google search and the resulting blogs, it appears that the left sees Miller and Kristoff as Right Wingers!! At least they appear to be more thoughtful critics of Iraq policy. It raises the possibility that they may have shared information.
I think it's more likely Kristof consulted Judith Miller about the matter. She had been writing about WMD's for a long time and would have had extensive CIA contacts.
Let's suppose, after the breakfast, Kristoff goes to Judith to bounce the story off her. It's possible Judith said something like, "Oh, his wife was there? She's CIA, you know".
But Wilson was caught off guard when around July 9 he received a phone call from Robert Novak, who, according to Wilson, said he'd been told by a C.I.A. source that Wilson's wife worked for the agency. "Can you confirm or deny?" Wilson recalls Novak as saying. "I need another source."