Third administration official outed Plame as well

"Mr. Pincus has not identified his source to the public. But a review of Mr. Pincus's own accounts and those of other people with detailed knowledge of the case strongly suggest that his source was neither Karl Rove, Mr. Bush's top political adviser, nor I. Lewis Libby, the chief of staff to Vice President Dick Cheney, and was in fact a third administration official whose identity has not yet been publicly disclosed."