I talked with some of my female friend who were studying CS, and asked them why they many of them gave up on programming and moved on to management or so other non-technical position.

The answer was that programming was boring and exhausting. From what I understand being code monkey who spends 40 hours a week debugging, writing crap code and checking tests with the most repetitive and non-creative manner doesn't gave them as much sense of an achievement as it gives to some men. Hell, I have doing that kind of job and only push on due to money and fact that 95% jobs in the area looks exactly like that. (And the rest 5% requires you tho know right people.)

I would say that there is relatively little of masochist women who would want to debug that race condition hell in C++/Java. There you have to endure a lot of frustration before reaching a (short) moment of satisfaction. On the other hand in some Rails startups that I know, where effect of your work was immediate and one didn't felt that she was hitting the wall all the time there was a lot more of girl programmers - about a half of the team. But there are very few of such startups in my neighborhood. All in all I've got more men around.

TL;DL - women are less of a masochist when it comes to frustrating jobs.