Rule number 1: Leaks from unnamed administrative sources are basically discounted, unless there is corroboration elsewhere.
Rule number 2: Leaks from unnamed administrative sources specifically identified by some job function (e.g., "former Congressional staffer" = Libby) are still discounted,... BUT
Rule number 3: Despite Rules number 1 and Rules number 2 (you'll note that "source familiar with the Fitzgerald investigation" or some such thing invariably means Rove's or Libby's Lawyer- Cheney's permanently in his hidey-hole (kinda like Saddam, no? oh, the irony...) and the only folks with authority to vet the kind of crap that goes out to the media are mouthpieces like Luskin. So, de-spin it for Rove, do a bit of what the Russians used to do reading Pravda, and voila! (French...there goes the irony again!) - some trajectory in the vicinity of what's going on. Or BS.
Rule number 4: Despite all the above, there are still pretty objective sources: Joe Wilson and Valerie Plame aren'tthe ones being considered for orange jumpsuits and frog-marches. Neither is George Tenet, who started this thing.
Rule number 5: Matthew Cooper has no real grist for BS-ing here. Judith Miller has to save face...strike that...she's toast, as toasty as if there were a video of her and "Pinch" Sulzberger engaging in sexual congress at the NY Times Christmas Party.
Rule Number 6: Some players, such as Chris Matthews (a.k.a., "Tweety" in Kos because of the way he flies from one position to another as well as being a reference to his hair color), Tim Russert, Ms. Allen Greenspan, and of course Robert Novak, know more about this then they let on since it's known that they've been leaked to as well (or at least that's what Rove/Libby has let on through their leaks) and if they didn't at this stage, have some connection, you can be sure that Fitzmas would include some obstruction charges specifically related to wild goose chases involving these reporters.