Let me try once more to explain. I feel a little misunderstood, even though I feel like I've been clear here.
Taking offense is a very subjective act.
It's entirely possible for me to offend someone without meaning to - it happens all the time because of cultural differences, or when people have different expectations of a situation.
In that situation, I tend to apologise, because I don't like offending people. It might be appropriate to just explain that no offense was intended, but not apologise. What is not OK is getting upset with the person because they were offended.
Now, let's transfer to this specific situation. I looked at the slides. I'm not offended by the slides, but I can certainly see how some people would feel uncomfortable with the bondage imagery. Apparently you are also not offended by the slides. Some people were.
Let's give a name to a hypothetical person who was offended - Anne. Anne comes from a conservative catholic family, and changes the channel on the TV any time scantily clad women appear on the screen. Anne is a 35 year old free software developer, mother of 2, big into her Ruby, and at her first tech conference. Anne didn't really like the playful S&M photo - it was outside her comfort zone. The language bothered her a bit, but you know, she can live with it. The road sign was funny. But Anne felt really uncomfortable with the lesbian bondage photo. And everyone around her seems to have no problem with it - they're well into the mood. So Anne feels out of place.
These are certainly sexualised images in public, and thus covered by the anti-harrassment policy.
Now, Anne's not the type of person to go blogging & tweeting afterwards, but (in considerable evolution on the part of our community) there are others who will.
My point is: it's not my place to tell Anne to get a life, that it's her problem. Anne felt uncomfortable, and now as an individual, I have a choice how to deal with that. I can deal with that by saying "Anne, you know, you're really not the type of person we were expecting", or I can say "I'm so sorry - we're making a real effort to reach outside our usual constituency, and we really did not want this to happen", or I can say "Anne, you're more than welcome here, but this kind of thing is to be expected - Mark was pushing everyone out of their comfort zone in some way".
Whatever I do, the fact that offense was caused cannot be undone by telling Anne to get a life (as I saw on Twitter), or calling her a "prude" (as I saw on the LCA chat list).
Have I cleared up any confusion on what my position actually is?
> You are joking? If not, your hypocrisy is staggering.
As Inigo Montoya said to Vizzini, "you keep using that word. I do not think it means what you think it means".