In better news
The GNOME Foundation released their conference speaker guidelines today. This is an important step not just in helping speakers know what's acceptable, but also in helping audience members understand in advance what the community is likely to find objectionable and ensure that they can feel comfortable in raising concerns.
Of course, guidelines mean little without enforcement. My original draft of these suggested that event runners be able to stop presentations if they felt they were gratuitously in breach of the guidelines. Opinions on this were fairly strongly split, with several people concerned that this effectively allowed individuals to immediately shut down presentations with little oversight. That's a genuine concern, but it does seem to assume bad faith on the part of conference organisers in a way we've rarely (never?) seen. On the other hand, conferences in our field have endured presentations that have contained offensive material from start to finish. If an offended individual is in a minority then it's not easy for them to potentially challenge the audience by vocally expressing their unhappiness, and even standing up and leaving may be a difficult and obvious act.
But I don't set the behavioural standards of the community, and attempting to enforce standards that people don't agree with isn't going to fly. Some people are likely to feel that even the level of enforcement suggested is an unwelcome intrusion into free discussion of some topics, so I think this is a good compromise that is a great signal for our unwillingness to accept inappropriate presentations. With luck we'll see other communities enact similar guidelines and we can come to a broad consensus that covers the majority of our conferences.