If Rove repeats that story on the witness stand, it could back up Libby’s core assertion that he honestly, if mistakenly, thought he had heard about Wilson’s wife from the “Meet the Press” host—even though Russert denies he knew anything about Plame, and more than a half-dozen officials (including Cheney) have said they passed along the same information to Libby earlier than that.
But the Rove account could cut in other ways. Fitzgerald would likely argue that Libby’s comment to Rove merely shows that the vice president’s top aide “was even lying inside the White House,” according to the legal source.
I don't see Rove as being a friendly witness to Libby, and I can't imagine Wells would want to take him on as a hostile witness. However, Rove has had memory troubles of his own in this case. Perhaps Team Libby just wants the jury to consider that everyone has had memory problems when it comes to who told who what with respect to Valerie Plame, but only Scooter has been charged with intentionally lying. If the only evidence Libby intentionally lied is witnesses' admittedly faulty memories, how can they find proof beyond a reasonable doubt?
On the other hand, that's why motive is so critical in this case. While it's not an element of any of the charged crimes -- meaning it's not something the Government is obligated to prove -- it could tip the scales for the jury one way or the other on credibility.
Update: On Ari Fleischer, Isikoff writes that "in the past, Fleischer has denied he had an attorney." I'm not sure what period he's talking about, but I remember reading that Fleischer had a lawyer but wouldn't give out his name to the media. I just found the quote in the July 28, 2005 NY Daily News (available on lexis.com),
LOWDOWN'S ALL-POINTS BULLETIN: For Ari Fleischer's mystery attorney. I hear that the former White House press secretary - who's been a grand-jury witness in the CIA- Karl Rove-Robert Novak leak brouhaha - refuses to reveal the name of his bill-by-the-hour legal adviser. Fleischer recently told a Washington reporter, "I'm not going to give you the name. It'll end up costing me money." I urge Fleischer's lawyer: Come forward and identify yourself. I want to have a long conversation with you.