I know no one will probably read this after 1,000+ comments, but I wanted to have my say. We've come a long way in a short time.
In the late 90s/early 00s, there was an article on Slashdot about how women were outnumbering men in the purchase of electronics and computing equipment. I remember jumping into the thread, thinking "Surely my enlightened brethren will celebrate this additional diversity in their field!"
Instead, I got comments about how women were clearly buying these things for their husbands, being misled by savvy (and male) salespeople, and some snarky comments about the nature of the "electronics" being purchased. (Either stoves, or washing machines, or something else that vibrates.) I got the feeling these techies were intimidated by someone else infringing on their territory. Yes, many of the comments were supposed to be funny, but they were clearly jokes laid thinly on top of sincere feelings. Now how do you think that made me feel about participating in this community?
Things have gotten much better since then, but don't you think the low percentage of women in the FOSS community may be related to some held-over, more open sexism from times past? Upon being burned once or twice, many women will just give up trying to be part of the boys' club. Additionally, though openly sexist comments are taboo now, the collective and subtle actions of an organization may all work together to feel a specific group feel unwelcome.
The commenters who are demanding specific examples of sexism (and when being provided with them, calling them single incidents not representative of the entire community) are misguided. The FOSS community doesn't need a witch hunt - it needs to look at the overall feel of the community and determine if something about that is exclusionary. It's not easy, and it's very warm-and-fuzzy, and many people in the FOSS community don't understand the problem if it doesn't consist of 0s and 1s.