now i'm confused... grey press is where your messages are anon, and black press is where they CAN be faked as being from someone else... right?

try this: http://www.vdiplomacy.com/variants.php#ClassicGreyPress

I believe orathic is partially correct. The line between grey and black seems somewhat blurry but is well defined.

In grey press, there is the ability to send messages anonymously, but otherwise, non-anon messages are reliably from the designated sender.

In black press, one may also spoof messages from another player. Note that one could spoof messages in grey press too, but if there is an option to also send non-anonymously then such messages would be noticeably unreliable.

The type of game that Stukus is suggesting perhaps should be classified as "public press only" and "grey press only". Since you are only allowing grey press, then effectively any message that is claiming to be from a specific player is like black press.
Also, since the channel would be implemented by a twitter account or blog, a player could potentially delete press as well, maybe before some of the players have seen it. I'm not sure if that's what you had in mind or what to call that.

Well we agree not to delete stuff beforehand. And I wasn't aware of grey press. In this game, no message is reliably from anyone. Every message has an anonymous sender. I guess you could spoof messages by signing off as another, which is what we did a lot.