In Talibanism in Technology, Deepa Kandaswamy lists seven reasons why women in technology remain invisible. Unfortunately, Deepa leaves out two important factors: interest and ego.
Most women I have met, regardless of age and background, are simply not interested in technology. While they do get impressed with latest electronic gadgets, they don't seem to get the same kind of urge that drove my son to spend an entire day tearing apart my old Dell laptop when he was 7 years old. Without that seemingly innate interest in technology, one cannot excel in it.
Also, most women seem to have relatively smaller ego-sphere (aka personal space) than guys do. Ego-spheres are present not just in the physical realm but also in virtual realms like CVS, history, and mindspace. Since most women seem not as interested in asserting their ego as guys, their presence in those virtual realms will be smaller.
Come on ladies, give Don a sound beating. He asked for it. ;-p
Thinking more about my comment on ego-sphere, I think guys give other guys more space than they would girls, probably to avoid conflict. When people sit down in a long chair like the one see in subway trains, guys sitting next to girls will open their legs wide but guys sitting next to guys will be more moderate.
Of course, there are tiresome jerks who break this unspoken rule. Tiresome because giving in to them is not an option. Being male is not easy.