What industry/profession are you in out of interest? I have heard friends talk about working in environments like this, but I have never experienced it. I work in the library sector. There are loads of women (including women bosses) and a big mix of ages etc. In every place I have worked it's been a really nice atmosphere and you just don't get bitchiness not even between the women in professional positions and those in the more dogsbody roles. I'd say that although the women I've worked with want to do well and move up the career ladder, you just don't get that nasty competitiveness. I have temped in offices though and experienced this atmosphere and it is horrible.
I wonder whether women behave like this sometimes because it is less acceptable for them to be openly competitive. One thing I notice about men at work is that they don't need to hide their ambition. They can be very open about how much they are going to fight for a promotion and I have worked with guys who would happily reel off a list of their talents/skills. So, I guess they kind of get it out of their system. If a woman walked around saying how wonderful she was or made it obvious she was going to fight for a promotion I feel she would be judged more than a man.