I disagree. That sort of slide (and its associated comment) is absolutely sexual harassment, in that it automatically sexualizes what is supposed to be a professional environment. Given the technology world's long and unpleasant track record of sexist behavior towards women (as well as towards... well, pretty much anybody who isn't, cisgendered, heterosexual, and male), I personally can think of very few ways that sexualizing a public technology presentation can do anything other than create (or contribute to) a hostile environment for a good chunk of the audience.
Furthermore, that sort of slide sends a clear message to the audience about who the speaker thinks they're speaking to. In this case, it says that the speaker thinks that his audience is composed of heterosexual males[1], which <sarcasm>I'm sure feels just great to any women who might also be in the audience.</sarcasm>
[1]: I'm going to go out on a limb and assume that the author of those conference slides did not include them in an attempt to appeal to the audience's lesbian members. I am, of course, willing to be corrected on this point.
We just need to recognize the difference between harassment and offensive.
I was not there, and I do not know if it was done in the spirit of things--had the conference been in Miami in August, bathing suit clad models wouldn't be terribly out of context--but if pressed to decide whether the presenter acted criminally or in bad taste, I'll err on the bad taste side.
Having said that, and having been to many conferences, and having had large staffs, I can say that I've seen both offensive behavior and harassment proper. I'm not a lawyer, and I've never been an HR professional, but my experience dealing with both tells me this specific situation would not have escalated. Perhaps poor judgement (context considered), but certainly not harassment.
I've read somewhere that using the words "offensive" or "offended by" puts the emphasis on the person who has expressed concern about the situation. It focuses on the negative: "what can we do to be less offensive?".
The article I read suggested using terms like "unwelcoming" or "exclusive" instead--as it puts the focus on the community. This allows us to focus on the positive: "what can we do to become more welcoming?".
So rather than considering whether this is a question of harrassment or offensiveness I find it useful to think of actions being "welcoming" or "unwelcoming" toward members of our community.
I don't see how you square that with the assertion that "harassment is not simply unwanted attention." Given that premise, it's almost an a priori fact that a sexualized environment is not cognate with harassment, since AFAICT the issue with a sexualized environment is that it brings or constitutes unwanted attention.
It might be uncomfortable, but it is not (in and of itself) harassment. Distinguishing is important, even if you agree that both are a problem.
Furthermore, that sort of slide sends a clear message to the audience about who the speaker thinks they're speaking to. In this case, it says that the speaker thinks that his audience is composed of heterosexual males[1], which <sarcasm>I'm sure feels just great to any women who might also be in the audience.</sarcasm>
[1]: I'm going to go out on a limb and assume that the author of those conference slides did not include them in an attempt to appeal to the audience's lesbian members. I am, of course, willing to be corrected on this point.