Apparantly females are more likely to use more emoticons in instant messaging.
I don't know if you can tell by poems and stories, but I think through instant messaging you do get a feel for conversation styles, and it may be much easier to tell female from male.. Just by how they respond.
I googled male /female brain test, and found this one;
BBC - Science & Nature - Sex ID
and I got 50% male and 50% female, and I prefer feminine faces (according to the test). That makes quite a bit of sense to me, I've got tenancies towards logic and emotion, and not really one or the other... But I wouldn't read too much into it still..