"This is because Judith Miller is the source of the leak to either Novak or Rove or Libby and Fitzegerald wants to know who is her original source how did she get the information about Plame."
I posted my last reply before seeing yours. Yes, I agree. This is the only thing that makes sense of the information we have to date.
Miller has gone to jail to protect whoever told her Plame was CIA--which was probably Plame or Wilson, but it could have been a pal of theirs. Or even someone at the CIA, who might have also known that Wilson was sent to Niger due to Plame's recommendation.
And she also doesn't want to let Rove off the hook. As long as this can play, the media thinks it will damage Rove. So it's win-win for the NY Times. The truth be damned.