Like Joel, I'm a fairly introverted person. Fortunately some research has been done on introversion, and we have an article explaining it: Caring for Your Introvert, The habits and needs of a little-understood group. A snippet:
Are introverts arrogant? Hardly. I suppose this common misconception has to do with our being more intelligent, more reflective, more independent, more level-headed, more refined, and more sensitive than extroverts. Also, it is probably due to our lack of small talk, a lack that extroverts often mistake for disdain. We tend to think before talking, whereas extroverts tend to think by talking...[via Chuck]