Sounds like the leaker (or should I say one of the leakers) has talked to prosecuters:

A Washington Post reporter’s confidential source has revealed his or her identity to the special prosecutor conducting the CIA leak inquiry, a development that provides investigators with a fact they have been pursuing in the nearly year-long probe.

Post reporter Walter Pincus, who had been subpoenaed to testify to a grand jury in the case, instead gave a deposition yesterday in which he recounted his conversation with the source, whom he has previously identified as an “administration official.” Pincus said he did not name the source and agreed to be questioned only with the source’s approval.

“I understand that my source has already spoken to the special prosecutor about our conversation on July 12 [2003], and that the special prosecutor has dropped his demand that I reveal my source. Even so, I will not testify about his or her identity,” Pincus said in a prepared statement.

The article goes on to say four of the reporters have testified that Scooter Libby didn’t leak the name to them.