Debugging conference anti-harassment policies

You imply that there is any consensus on what
"workplace-rules" are.

I'm constantly baffled by "Not Workplace Safe"-
disclaimers in blogs and news sites, and concluded
that this "workplace" they're referring to must be
somewhere else, probably in the USA.

So you've got exactly the same underlying cultural
differences as everywhere else, and as are mentioned
by various commenters in this thread. There's apparently
a vast difference between Europe and the USA, and we
haven't even mentioned Japan yet.

Speaking of looking at porn in the workplace: I used
to work at a large webhosting company, which had
porn-sites among it's customers. Of course you sometimes
had to look at porn to help them debug their php-problem.