Since I promised to post this, here's Christina Haralanova's master's thesis on women in the open source community: http://www.ludost.org/content/release-10-womens-contribution-free-and-op...
The document is in French. I hope to find the time to write an English summary at some point, and Christina also hopes to translate the entire text if she finds the time and/or money to do so. In the meantime, here it is for those of you who do read French.
Very, very quick summary: women actually contribute far more to the open source software community than most people realize, but as men make up a disproportionate number of the lead programmers on most projects, women's work tends to not be as visible or valued.