It's not the color. It's the statement you're making when you choose a color unlike most other phones out there. It could be blue, for all it matters. The fact that you care enough about fashion that you'll choose the non-serious businesslike black phone gives you a feminine quality.
All the people going nuts over black iPods, when they first came out, is just another example. The people who stuck with boring old white were showing they didn't care about fashion, whereas the people getting black were caring perhaps a bit too much about how it would look and less about manly things like efficiency and gigabytes.
Think about it like this. When you go to a fancy dinner party, men are all wearing dark colored plain suits, and women are dressed in all sorts of exotic colors. It's because men keep things simple, and women care more about showing off how they look.