The question isn't whether these governmental sources told Libby about Plame, but whether he had previously heard it from reporters or "in the wind," perhaps totally unconnected to the Niger story.
No the problem is that Libby specifically said that he learned about Wilson's wife in talking with Tim Russert on a specific day. He has to show that Russert was lying or that he has to come up with other reporters who will testify that they told him. Good luck there.