So we all know the sinking feeling -- you want to be friends with the other woman at work but you feel like she thinks of herself in direct competition with you (or worse, subtle things start adding up)...
Why does this happen? I have seriously met women who, it seemed to me, looked at life as if we were back in the harem and only one of us was going to bear the royal son. I can't really understand this attitude and luckily most women I meet aren't like that, but a surprising number are.
Here's an interesting article in the NYT which doesn't give many answers, but describes the phenomenon rather well.
http://www.nytimes.com/2009/01/11/jobs/11pre.html