Joel Achenbach has some quality snark in the Washington Post:

Somewhere along the line the Valerie Plame leak probe became a daily story, something in which every incremental development — even a new leak from another mysterious source “with close knowledge of the thinking of investigators,” and so on — is worthy of another trip through the trap door and down the chute into the dimly lit bunker of InvestigationWorld. You can read all these stories with Talmudic seriousness and never know what the heck is going on. What is special prosecutor Patrick Fitzgerald after? Or, more precisely, who? The articles seem to be edging closer and closer to the suggestion that the ultimate target may be someone much higher in the Administration than, say, Karl Rove or Scooter Libby. My own suspicion is that this case may go even higher than Bush — that it may go all the way to Cheney.