Today's Newsweek tells us that Matthew Cooper's source was Karl Rove. But the writing is carefully contrived so as to not accuse Rove of having done anything illegal:
In a brief conversation with Rove, Cooper asked what to make of the flap over Wilson's criticisms. NEWSWEEK obtained a copy of the e-mail that Cooper sent his bureau chief after speaking to Rove. (The e-mail was authenticated by a source intimately familiar with Time's editorial handling of the Wilson story, but who has asked not to be identified because of the magazine's corporate decision not to disclose its contents.) Cooper wrote that Rove offered him a "big warning" not to "get too far out on Wilson." Rove told Cooper that Wilson's trip had not been authorized by "DCIA"—CIA Director George Tenet—or Vice President Dick Cheney. Rather, "it was, KR said, wilson's wife, who apparently works at the agency on wmd [weapons of mass destruction] issues who authorized the trip." Wilson's wife is Plame, then an undercover agent working as an analyst in the CIA's Directorate of Operations counterproliferation division. (Cooper later included the essence of what Rove told him in an online story.) The e-mail characterizing the conversation continues: "not only the genesis of the trip is flawed an[d] suspect but so is the report. he [Rove] implied strongly there's still plenty to implicate iraqi interest in acquiring uranium fro[m] Niger ... "
Nothing in the Cooper e-mail suggests that Rove used Plame's name or knew she was a covert operative. Nonetheless, it is significant that Rove was speaking to Cooper before Novak's column appeared; in other words, before Plame's identity had been published. Fitzgerald has been looking for evidence that Rove spoke to other reporters as well. "Karl Rove has shared with Fitzgerald all the information he has about any potentially relevant contacts he has had with any reporters, including Matt Cooper," Luskin told NEWSWEEK.
The crucial bit here is in the last paragraph: "that Rove was speaking to Cooper before Novak's column appeared". Earlier it was said that he only commented on the issue after the Novak column, which would then have been his source.
So much depends on the prosecutor's guts in this case. We'll see.