Ooh! Now we're getting into semantics. My take on that would be that post-operative transexuals are neither gender, having neither ovaries nor testicles, but I suppose by that reasoning, castrati and women who've had hysterectomies would also be of neither gender.

I like the definition cyndylu provided for us, though I think I've also heard a different word used to describe "one whose primary sexual identification is with the opposite sex".