Remember Ambassador Joseph Wilson? He's the man traveled to Niger and refuted the Yellowcake claim a year before the State of the Union address. Shortly after Wilson revealed that the Bush administration lied in June, Robert Novak reported that Wilson's wife was a CIA operative (she was undercover, and leaking her name and status is illegal). Well, according to CBS News, the Justice Department is investigating whether the White House leaked her name in order to intimidate others in the CIA from coming forward and telling the truth about their lies. Wilson's wife's career is effectively over as an undercover agent since being outed by Novak (and whoever leaked the information). This could be the beginning of a scandal, or it could just die off. Either way, Bush will get more negative press in the coming days, and the yellowcake will come back into the news.
Political consequences: Even if Bush or anyone in his administration aren't charged with anything, this will further erode Bush's trustfulness, a key factor that was holding his poll numbers up. I seriously doubted Bush could go any lower than 49 at the current time, but after this, I think he could very well dip down to about 40-43% approval.