Are we talking physical appearance or personality as well? I don't fit either, really.
My idea of IT stereotype:
Generally clean but somewhat wrinkly clothes at times that almostmatch
Somewhat disheveled look
Doesn't shave for long periods
Somewhat strange body language/awkward around groups of people not in IT
Unable to communicate in non-technical ways (e.g. speaking to the target audience)
Inability to admit when they aren't aware of a new technology
No real sense of humor
Sense that everyone reads slahdot on a regular basis
Quote Bruce Schneier in e-mail footers
That is how most people in my IT department are. I don't work in the actual department, thank God.