I'm guessing never

David Corn obviously is not reading David Broder or he would know the thing he is supposed to do as a reporter is apologize (genuflect, and perhaps a reacharound) to Karl Rove:

Which brings me to a rather simple question: [since Armitage apologized] When will Karl Rove do the same?

He is no longer under investigation. But he did play a critical role in the leak case by confirming Armitage's information for Novak and then (before the Novak column appeared) leaking the same classified information to Matt Cooper of Time, as part of a campaign to discredit Joseph Wilson. (Hubris--which chronicles the behind-the-scenes battles in the CIA, the White House and Congress in the run-up to the war--has new details on Rove and Scooter Libby's efforts to undermine Wilson.) So will Rove now explain precisely what he did and why he did it, as Armitage has? Is he willing to admit he mishandled state secrets? Is he also sorry? Will he apologize to anyone?

Once upon a time, President Bush said he wanted the truth about the leak to come out. Libby, who is facing indictment for having allegedly lied to FBI agents and a grand jury about his involvement in the leak episode, may feel he is in no position to emulate Armitage. But Rove is not so encumbered.

What reason might Rove have for not following Armitage's lead?

How dare Mr. Corn use things like facts considering the importances of Mr. Broder's beloved version of the "iron triangle" (Government, Punditry, Cocktail Shrimp).