Both groups are self-selected, though one of the samples is larger. But I've no reason to doubt the numbers--they seem to be in the right ballpark. In a competitive, technical community like this one, 2-5% women is about what experience tells me to expect. Fighter pilots are a similar, if more extreme, example: http://userpages.aug.com/captbarb/fighters.html
The phenomenon simply is what it is -- I do not know or speculate on the cause. But I find it fascinating that many people feel compelled to quickly invent stories to explain it away. A little encounter with heresy seems to provoke a defensive rush into mythology.
I think a little cognitive dissonance, a little acceptance of heretical fact, a little uncomfortable admission of ignorance, is good for intellectual hygeine; I welcome and cherish odd little phenomena like this, even if--in fact, especially because--they run so counter to my beliefs and expectations.
Not sure what the point you are trying to make - there is a huge difference between 2% and 6% (factor of 3 to be precise). I personally would think it would be 5% at least, so I chose to believe the poll that confirms my preformed opinion :-)
You mean: http://news.ycombinator.com/item?id=749617 ? There, female was about 6%.