I don't quite agree with him though - and from his CV, he's interned a bit (in highly prestigious companies), but never actually worked in industry...
I virtually am that first paragraph (only poorer, so normal Uni, no modem for BBSes etc), and I would say that I actually experience less sexism (bias when employing etc.) in IT, and from men in IT than I have when in non-tech roles (eg. retail).
At Uni, I was one of 2 or 3 girls in most of my lectures (the only one doing my course, but we shared some modules with maths and electronics), my hobbies were generally male dominated, my work life has been generally male dominated, but the people I encounter day to day in these geeky work and hobbies, whilst being shocked to see me sometimes, and often romatically approached as the only available girl, I've never had a pushy attempt, I've never been told I shouldn't be doing something because I'm a girl, I've never been pushed into certain roles except by non-techies/geeks (eg. company manager expecting me, Head of Development, to take meeting minutes because I was the only woman present).
All I had was an interest in Computers, and a willingness to take a deep breath and walk into a room full of (perfectly nice, if odd) blokes (repeatedly.. throughout my learning and career). Far more nervewracking to walk into a bar full of normal men, who make jibes, inappropriately touch and can actually hurt you.
In my opinion, we've lost the girls far sooner than college and high school. We've lost them when the kids group around the console at Christmas, but the girls aren't taught to be assertive and demand their turn. Or when mediocre boys somehow have the confidence to carry on programming/playing games but the girls rate their skills as too low to pursue it - most programmers are mediocre and it's fine (most jobs are pretty mediocre too). I see it in my son - he's been taught to share too much, so now I need to teach him to push forward and demand his turn - girls need to be taught the same.