According to Capital Games (a Nation column), the White House may have punished Ambassador Joseph Wilson for undermining their deniability in the Yellowcakegate scandal:
Soon after Wilson disclosed his trip in the media and made the White House look bad. the payback came. Novak’s July 14, 2003, column presented the back-story on Wilson’s mission and contained the following sentences: "Wilson never worked for the CIA, but his wife, Valerie Plame, is an Agency operative on weapons of mass destruction. Two senior administration officials told me Wilson’s wife suggested sending him to Niger to investigate" the allegation. Wilson caused problems for the White House, and his wife was outed as an undercover CIA officer.
If true, this recklessness in the interest of political tactics is seriously troublesome.