My shyness has been melting for the past six months, but I'm still a bit reserved. Unless I'm with a group of people I know (like in class or whatever), then everyone thinks I'm an extrovert. But I'm not an extrovert - too much stimulus exhausts me. I'm just more comfortable in certain situations is all. And what people take to me being extremely funny and gregarious is really me relieving my anxiety by being a smartass.
Pretty much the same for online. My personality is better suited to online life.