Before I posted a pic, it seemed most people thought I was male. I remember the first time I spoke on ventrilo someone going, "Holy shit, you're a girl."
And I think a lot of people didn't see the pic, so I still got a lot of "Oh, I thought you were a guy" after that.
I think, as a standard, people will automatically assume male for most posters unless you have a obviously feminine name and avatar.
“Everybody has a secret world inside of them. All of the people of the world, I mean everybody. No matter how dull and boring they are on the outside, inside
them they've all got unimaginable, magnificent, wonderful, stupid, amazing worlds. Not just one world. Hundreds of them. Thousands maybe.” -Neil Gaiman