women talk/post differently when they're away from men-- directly and without emoticons. I haven't spent enough time in all-women groups to have an opinion about this.

A data point: My friend often writes on a "website for mothers", and they have a lot of emoticons (and animated!) and use them often. (Here; ignore the language, just click on a few random articles and scroll down to comments.)

I would say that some women speak and write as your friend describes (simply because not all women are the same), but many women use the "feminine" way of speech/writing, and it's not only when men are present. Perhaps for some of them this is natural, and others only use it strategically in presence of men.