Well, Wilson himself says Novak told him he obtained the information from the CIA in the excerpt from his book below. [How Wilson came to blame Rove for the leak of info I am not sure unless maybe he thinks Rove is CIA or thought no one would compare his claims to past statements and catch him in the lie.]
JULY 10, 2003 : (THE DATE JOE WILSON CLAIMS HE AND NOVAK SPOKE ABOUT JOE WILSON'S "FRIEND'S" ALLEGED ENCOUNTER WITH NOVAK ON JULY 8) Novak called the next morning [July 9], but I was out, and then so was he. We did not connect until the following day, July 10. He listened quietly as I repeated to him my friend’s account of their conversation. I told him I couldn’t imagine what had possessed him to blurt out to a complete stranger what he had thought he knew about my wife. Novak apologized, and then asked if I would confirm what he had heard from a CIA source: that my wife worked at the Agency. I told him that I didn’t answer questions about my wife. I told him that my story was not about my wife or even about me; it was about sixteen words in the State of the Union address.
I then read to him [* My note- why? Ego?] three sentences from a 1990 news story about the evacuation of Baghdad: “The chief American diplomat, Joe Wilson, shepherds his flock of some 800 known Americans like a village priest. At 4:30 Sunday morning, he was helping 55 wives and children of U.S. diplomats from Kuwait load themselves and their few remaining possessions on transport for the long haul on the desert to Jordan. He shows the stuff of heroism.” The reporters who had written this, I pointed out, were Robert Novak and Rowland Evans.
I suggested to Novak that he might want to check his files before writing about me. I also offered to send him all the articles I had written in the past year on policy toward Iraq so that he could educate himself on the positions I had taken. He would learn, if he took the time, that I was hardly antiwar, just anti–dumb war. Before I hung up, Novak apologized again for having spoken about Valerie to a complete stranger. ----------- "A Strange Encounter with Robert Novak ," from Chapter 17 - The Politics of Truth , by Joseph Wilson, http://www.politicsoftruth.com/excerpt.html