My thoughts on the subject are:
1) There is a gender imbalance in the tech community, regardless of how you slice it (e.g. founders, developers, etc.).
2) Many people when faced with what they perceive to be sexist language, take it to be a political statement rather than the idiotic flyer (as in this case) or the casual blog comment(e.g. http://news.ycombinator.com/item?id=3602762, which caused a firestorm on HN) that it is.
3) Don't get me wrong: I'm against crude use of sexisms such as this one, GoDaddy commercials, photos of women in bikinis on Rails conference slides, booth babes. The point is that these offend not only my anti-sexist sensibilities but also my intelligence, so even if I were sexist I would still be offended by these and ask for their removal, on the grounds that they show that the mental model of me that the people responsible have is a brainless, easy to manipulate moron.
4) However, thinking that eradicating the above will lead to considerably more women in tech, I think, is mistaken. I believe addressing the issues that are less obvious but more influential in consciously or subconsciously turning off women is more important, e.g. rather than getting worked up when somebody uses the word girl in a post, thinking about the "cool" but male-oriented terms like code ninja that are prevalent in job postings (e.g. all of the 10 types of programmers mentioned here are all male oriented: http://www.techrepublic.com/blog/10things/10-types-of-progra...).
