leaker confidential

I remember in my media law course discussing leaker confidentiality. As you know, much of our juicy information comes from a "senior administration official." Reporters refrain from id-ing the leak for fear of losing future leaks. It's a subject close in kin to lawyer/client, doctor/patient, and president/advisor confidentiality. The idea is to promote candid communication between the parties.
For a reporter's perspective on the issue, I commend Josh Marshall. His post, today, contemplates the two reporters threatened with contempt (more specifically, jail time) for failing to identify a leaker in the Valerie Plame affair. Marshall has watched the issue particularly and wants some conclusions; however, the reporter in him supports the reporter that faces contempt. A good read on the subject.