Time Magazine reports that a federal grand jury has begun hearing testimony in the investigation into the leak of CIA operative Valerie Plame's identity:

Prosecutors are believed to be starting with third-party witnesses, people who were not directly involved in the leak of Plame's identity. Plame's husband, former Ambassador Joseph Wilson, claims that the leak was an act of retaliation against him for undercutting Bush's weapons-of-mass-destruction rationale for going to war in Iraq. Soon enough, witnesses with more direct knowledge will be called to testify, and a decision to subpoena journalists for their testimony will also be made.

[link via Atrios.]

Congress is considering launching it's own probe into the leak:

Members of Congress and 10 ex-CIA officials are seeking a broader inquiry into the leak of an undercover officer's name, aiming to determine if U.S. national security was compromised and to discourage future leaks.

In addition, a leading Democratic critic of the Justice Department investigation into the matter says the Bush administration should release details of the probe to show the public whether officials are cooperating as President Bush promised.