Not since Charles Foster Kane's immortal "Rosebud" has a deathbed utterance caused such a stir. CIA Director William Casey, partly paralyzed and gravely ill following brain surgery, was in Washington's Georgetown University Hospital last winter when an unexpected visitor entered his room. It was Washington Post Reporter Bob Woodward, who had interviewed Casey off and on for four years and had somehow slipped through CIA security for one last encounter. So Woodward says in his new book, Veil: The Secret Wars of the CIA, 1981-1987 (Simon & Schuster; $21.95), relating that the interview lasted just four minutes and Casey managed only...