Outside the conservative media and the blogosphere, you're unlikely to know that Valerie Plame's "cover" (and I use that term loosely) was blown long before the Novak column, or that phone conversation between Matt Cooper and Karl Rove.
NRO has a couple of excellent columns that provide the "rest of the story," predictably ignored by the MSM. Cliff May correctly notes that the first journalist to expose Ms. Plame as an agent with "Non-Official Cover" (NOC), was not Bob Novak, but David Corn, a columnist for the ultra-liberal The Nation. In the Novak column, published on July 14, 2003, Ms. Plame is referred to as "an agency operative on weapons of mass destruction." The first reference to her prior status as a NOC operative didn't come until two days later, when Corn published his piece in The Nation. Novak has maintained that no one ever told him of Ms. Plame's career as an undercover operative, and his column reflects that. In laymen's terms, everyone employed by the CIA is an operative, despite the fact that most agency personnel work outside NOC channels.
In a companion piece, Andrew McCarthy provides hard evidence that Plame's "cover" was blown by the CIA in the mid-1990s, almost a decade before she recommended her husband for that infamous trip to Africa. In fact, Bill Gertz of the Washington Times reported (about a year ago) that Ms. Plame's identity had been exposed not once, but twice. And, as McCarthy notes, the MSM has reached new heights of hypocrisy in stoking the Plame kerfuffle. When Cooper and Judith Miller of The New York Times were first threatened with jail for defying the subpoenas of the special prosecutor, attorneys for a number of MSM outlets filed an amicus brief with the U.S. Court of Appeals in Washington. In the brief, the media organizations contended that Cooper and Miller should not be subject to sanctions because no crime had been committed in the Plame affair.
But when there's a chance to scalp Karl Rove--or other members of the Bush Administration --the MSM never lets the fact (or their own legal arguments) get in the way of the "gotcha" game. That means they'll try to sustain the scandal for as long as possible, hoping to build a public groundswell that will (ultimately) force Rove, Scooter Libby, or someone else to resign.
IMO, that's unlikely to happen. A more likely scenario is the eventual indictment of Joe Wilson (or a Democratic operative) for lying to the grand jury, and possibly, obstruction of justice. When that happens, the investigation--which the MSM and Washington Democrats clamored for--will become a "witch hunt," and Wilson will morph into a latter-day Alger Hiss (presumably after his stint in federal prison)