In a well-reasoned op-ed piece for the New York Times this morning, Geneva Overholser calls for Bob Novak to voluntarily reveal the name of the Valerie Plame leaker, before a grand jury asks him to:
http://www.nytimes.com/2004/02/06/opinion/06OVER.html?th
In addition, she makes a nice argument for why it's sometimes more ethical for a journalist to reveal a source than to protect it.
She's no tinfoil-hatter either; this is her bio lifted from the page: "Geneva Overholser is a professor at the University of Missouri School of Journalism. She is a former editor of The Des Moines Register, ombudsman of The Washington Post and member of The New York Times editorial board."