Lately, there's been a lot of discussion about gender and sexism in the engineering blogosphere, particularly at Engineer Blogs and FrauTech's response to some of the fallout here.
Here's the thing I've noticed, though: we may all be engineers, but different disciplines have very different gender dynamics.
My undergraduate institution was almost entirely engineering majors, with an overall 3:1 male:female ratio. In some departments (like mine), there was gender parity, and in biomedical engineering, women actually dominated. On the other hand the "big" departments, EE and MechE, were very male dominated.
Consequently, the environment I experienced was very different than my female counterparts in EE, or Computer Science. I had other women to study with, but I also never had issues where the men were trying to prove they were smarter. I attribute part of this culture in the department to our fabulous undergrad lab technician who rules with an iron fist and the best brownies on the planet. Another thing is the small class sizes. I took almost every class my junior and senior years with the same 35 people. We had a pretty good idea of who was good at what, and there was a sense of camaraderie I didn't see in the larger departments.
The ME and EE departments had more female professors, but also tended towards massive lectures without much interaction. It's very easy to go the entire semester and never learn anyone else's name in the room. The environment was also much more intensely competitive, with more professors grading on curves. In the smaller, higher level classes, many of the female students had just gotten used to never speaking up, and apparently had fallen into the habit of sitting quietly and keeping a low profile. I took a higher level Photonics class, with the only other female in the room a native EE student. At the beginning of the semester, she took the quiet route. I, on the other hand, coming out of a very different environment, had gotten used to speaking up and raising my hand. As the semester progressed, she seemed to come out of her shell and get more engage in the class.
I really believe that xkcd captured it perfectly. If there aren't many women, each one feels as if she has to represent the entire gender. When women make up almost half the room, though, it's easier to escape that mindset. This is why it's critical to get more women into engineering in the first place: to reach the threshold where women have a support network.