Females in IT are not rare sight over here in the west coast. I don't know what percentage they build up here where I live, but I can tell you this much, a woman is more likely to sit down and read the manual from left to right and be very delicate with the hardware.
Of course, the emotional content is different. So, really, I think it's a matter of there qualifications and ability to work on a piece of equipment and the ability of the employer to see that they are indeed a capable individual.
With that said, a lot of the reason why I became interested in computers was behind my mother and father, mother worked for McDonald Douglas and NASA, then apart of there engineering/rocket division, she had to quit because of the military involvement with a recent move to her new department.