Doesn't anybody notice - this purported conversation was held weeks before Joe Wilson's article was even published!
ping
Joe Wilson hadn't been "published"...but he had been leaking "anonymously" for two months.
Nicholas Kristof's column of May 6, 2003 provides a description of his source that would effectively finger Wilson -- if anybody was interested enough to do a little digging.
Indeed, Cheney and Libby probably were aware of Wilson by this date. After all, the "anonymous source" was claiming that he had been "sent by the Vice President". Damn right, Cheney would want to know who this fool was.
I don't think that signifies. Okie01 says that Wilson had been leaking for months. I would add that these coordinated attacks on the Bush administration usually involve planning sessions among the instigators--in this case certainly Wilson, but also the NY Times OpEd page editor, various reporters who were in it from the start, and probably a few senior editors and publishers.
Major MSM propaganda campaigns--in this case, the "Bush lied about WMDs," which then morphed into Plamegate--are usually orchestrated by a number of players in the media and the political world, working together.