I like jokes like these: http://www.youtube.com/watch?v=0BxckAMaTDc
By all means women speakers should make similar jokes instead of overreacting.
I get the feeling that some women just can't take a joke. Of course there are more serious cases, but stuff like this should be ignored.
I understand that the lack of women in tech(especially open source) is a barrier to entry for women, but reactions like these only make that barrier wider. I once read a story about someone who said will never hire a black person, because if he ever fires him for some reason, the guy will come back with his lawyer and say he was fired because he was black.