I've done a fair amount of roleplaying in chat rooms and on forums. And at the moment, I think I've made about 4 male characters, compared to the 7 or more female ones. Given that I'm a guy, there's a lot of people who think that's sort of weird.
Thing is, I generally find it easier to get into a female character's mind and be able to roleplay them properly. I'm pretty sure it's because I'm a sort of "feminine" guy. So, in my opinion, there's nothing wrong with roleplaying the opposite gender, and it should really be more encouraged as long as it's done well.