Do women, on average, have more connected social lives than men do? It's very easy for a few people with no life to effectively dominate a community like this simply by spending more time than any "normal" person would want to. If women are more likely to have "a life" and less likely to become fixated on a specific hobby, that could explain why we see fewer women commenters. (One reason I'm here is that I have very few people in Real Life that I talk to regularly.)

A possibly relevant data point is that males are roughly four times more likely to have autism or Asperger's syndrome than females.