Come on, let's not be coy about this. The particular issue that philwelch is referring to is not that of women, but of blacks. Women have a completely different set of reasons for why they don't achieve as much career-wise as men, despite similar levels of education (the first thing that comes to mind is of course the time demands of child-bearing/rearing).

But for blacks, there definitely is a "pipeline problem." The quality of education available to the average black child is much poorer than that available to the average white child. Although there is definitely both conscious and subconscious discrimination against blacks, in the enterpreneurial industry as well as a raft of others, the biggest chunk of the problem can be attributed to subpar education and a culture that actively discourages success through math/science/engineering.

If we really want to understand what's going on we need to look at areas that attract more women than men. It turns out that the northern Virginia area has a significant female bias where there are far more young well educated females than you would expect based on graduation rates etc. Perhaps the prospect of a safe 80+k job in a good area acts a golden handcuffs that prevents many young capable women from 'seeking their fortune'. But, good or bad, cultural or biological, it's not simply a question of employer bias, people chose the areas they want to live in far more than they are force into or out of a specific region.

Further, pg somewhere argued that there's a multiplicative factor once you factor in cofounders--cofounding a startup implies an extremely close platonic relationship, people are more likely to form extremely close platonic relationships with members of the same sex, and hence men have a wider range of possible cofounders than women. I think this argument is at least partially flawed--many businesses are started by husband-and-wife teams and there's no clear reason why opposite-sex platonic cofounder relationships couldn't work either.