I think you may be surprised by the Open Source community. One of the leaders on the gender session at Africa Source, Fernanda Weiden, explained to us exactly how it felt joining certain communities on freenode, for example, and how being female affected the way people interacted with her, and so forth. That's something that guys don't have to deal with, and as such is a form of discrimination (which, ultimately is just behaving differently based on a characteristic).
Or, as you mention, it's not so much intentional discrimination as an intimidating environment. The off-topic gender-based jokes on one LUG have led to a number of women leaving the group, for example. These weren't necessarily IT professionals, but they were interested enough to have Linux installed at home and to join a user group; exactly the people we need to keep advancing through the ranks. Hopefully they found homes elsewhere.
(I guess that's what I meant about the culture becoming more "mainstream". The tech and Open Source communities I've been a part of were a lot more accepting of, for example, gay or transgendered members, than the mainstream then. But that gap is closing as tech and Open Source become more mainstream. Or I've just been unlucky in my choices of communities.)
Back on work: one study that the other session leader related found that women tend not to over-inflate their ability, while men tend to do so by about 25% (IIRC). This leads to less self-advertising and thus less promotions and opportunities in the work-place.
I suppose I just question the need to simplify or change the subject matter. I don't believe that there's anything inherently masculine about it, it's currently equally available, and there's only a little that one can focus on female issues that aren't just generally useful. I think the gender divide boils down to social acceptance, community, role models, and work environment, all working towards self-acceptance. Work on those, and we'll speed up the inevitable change.
Perhaps humanisation should be focussed on the workplace/community - a sensitivity for the way that women tend to behave differently from men. Understanding that women might be a little less likely to brag, for example, would be useful for decision makers to decide on job applicants, promotions, and other opportunities. Understanding that confrontational styles would probably not be very effective with women too - although I think that's just a generally good idea. Understanding that inviting "The Boys" to the pub every Friday afternoon is just creating the impression of a "popular" sub-group unless other activities are found to bring in those who feel left out.
But, as I said, I come from a pretty feminist position, so we may just be talking past each other on the basic causes.