This was theoretically a professional partner event. You wouldn't get a comedian on stage cracking racist jokes at those, so why should sexist jokes be acceptable?

Perhaps you should actually read the original report by the Danish blogger: http://elektronista.dk/kommentar/dresscode-blue-tie-and-male...

Then, perhaps, you should put yourself in women-in-tech's shoes and ask yourself why this might be offensive. We're a small minority which is, on the one hand, desperately in need of encouragement, yet, on the other hand, continually set back by the sexist, intimidating attitudes of some men in the industry.

For some other examples you might want to see http://programmersbeingdicks.tumblr.com/