Unlike personality classifications (which are essentially witchcraft with better marketing), gender is objectively verifiable (yeah yeah gender studies students, I passed the class too, thanks for your comment) and so makes for a much more productive area of research. Trivial algorithms (~60 lines of awk last time I did it) are very capable of pegging gender with 80%+ accuracy for some corpora.

See generally: http://u.cs.biu.ac.il/~koppel/papers/male-female-text-final....