I just registered. This looks like a great forum! I'm really interested in the ethics of various types of sexual/family relationships. It's so good when people take the responsibility to openly discuss polyamory concerns instead of just seeing what they can get away with secretly without any concern for the consequences or anyone else's feelings.
Anyway, in response to this thread I think that it is reasonable to expect one's partner to be free to talk about whatever they're doing with other people with other partners. Of course, it changes things a bit when people are using your openness to spy on you. I think when you openly agree to having multiple partners, you should also feel comfortable talking about each other with each other as long as there is mutual respect. Keeping secrets is usually more painful than the information that is being kept secret, imo.