This is interesting. It looks like Libby was not the first official to reveal to a reporter where Plame worked: A Washington Post story claims this: "Washington Post Assistant Managing Editor Bob Woodward testified under oath Monday in the CIA leak case that a senior administration official told him about CIA operative Valerie Plame and her position at the agency nearly a month before her identity was disclosed.

In a more than two-hour deposition, Woodward told Special Counsel Patrick J. Fitzgerald that the official casually told him in mid-June 2003 that Plame worked as a CIA analyst on weapons of mass destruction, and that he did not believe the information to be classified or sensitive, according to a statement Woodward released yesterday." And then this:

"Fitzgerald interviewed Woodward about the previously undisclosed conversation after the official alerted the prosecutor to it on Nov. 3 -- one week after Vice President Cheney’s chief of staff, I. Lewis ’Scooter’ Libby, was indicted in the investigation."

As one wag puts it, "What else did Fitzgerald not know, and when did he not know it?" More here.
This might be fun.