Looks like in both cases, there's an exception if either party (sender or recipient) grants access to a third party, so this shouldn't apply to the Post unless they accessed the account without MD4BUSH's permission.
Unless you consider the username/password the property of Free Republic. In which case any of us sharing that info without FR permission would be a violation of FR rules. I'm still not sure how the law fits into the equation, but I'll bet that's why JR is seeking legal council.
According to the Washington Post - "Brenner said The Post does not know the identity of MD4BUSH, which the newspaper also has reported."
If they didn't know his identity, how could they receive his permission? How could they know if the intermediary was authorized to act on the unidentified person's behalf?
If I approached you claiming to represent an unidentified third party and provided you the password to his private email account, would you believe that constituted permission for you to use the password to access the account? Wouldn't you want to confirm the identity of the person and obtain direct authorization before using the password?
Does the ECPA have an exemption that allows Washington Post reporters to use passwords to hack into an unidentified person's private e-mails without proper authorization - then publish them in the newspaper? Hell no it doesn't!