Suspect #3.Cooper himself.
The language of the email is ambiguous. It's possible that all Rove said was "Wilson's wife authorized the trip." The "who apparently works at the agency on wmd issues" clause could just be Cooper's own background knowledge. It isn't clear from the email.
yes, Cooper himself. since everyone in Democrat Washington anyway knew who Mrs Joe Wilson was, why wouldn't Cooper just fill in the name from his own knowledge? no actual leak at all>
Very good point. We need to remember that these guys work at manipulating words for a living.