A referral to the Justice Department that Valeri Plame's covert status was illegally divulged.
Who instigated it?
The Novak column stated that Plame worked for the CIA. The DEMs and the media whipped up a firestorm that this revelation involved a criminal leak of confidential information. The CIA prepared and sent the referral.
Justice launches probe into CIA leak - October 1, 2003 <- Some details
And what were the results?
Fitzgerald, the special prosecutor, has not announced any results. There is rampant speculation as to whether Plame was in fac covert (i.e., whether or not there is a violation of law); as well as to who the leaker was in any event. The DEMs and the media assert that no matter what, Rove's conduct in acknowledgement, even if he wasn't a leaker, merits dismissal from his post.
Nice answers, thanks.