I posted that many times in the run-up to this. The answer I always got (which is true), is that guys like Rove and Libby - its THEIR JOB to talk to the press. Its one of the things they do.
The press set these guys up. All these people - Miller, Cooper, Russert - they all knew Wilson's wife was CIA before baiting Rove and Libby when talking with them about the Wilson affair. Now of course, we can't PROVE that (because no one is investigating it). But we can just look at the Andrea Mitchell comment for example about the DC cocktail circuit knowing Wilson's wife was CIA, to guess that Cooper, Miller, and Russert also knew that going into this whole thing.
Pick your reporters you talk to wisely -- NY Times Cooper was not a wise move IMHO.