In a post earlier this year, Mike Davis busted the myth that only extroverts make good leaders. He even provided you with some tools to help you assess whether you're an extrovert or an introvert.
In the same vein, I want to point you to a great post on another blog. Graphic designer Eli Bishop has written 10 Myths about Introverts. It provides a lot of great information about what introversion is . . . and what it isn't. If anything, it may help you to identify whether you're an introvert. Here's an excerpt:
Introverts are people whose energy tends to expand through reflection and dwindle during interaction. They often take pleasure in solitary activities such as reading, writing, music, drawing, tinkering, playing video games, watching movies and plays, and using computers. The archetypal artist, writer, sculptor, engineer, composer, and inventor are all highly introverted. An introvert is likely to enjoy time spent alone and find less reward in time spent with large groups of people. They prefer to concentrate on a single activity at a time and like to observe situations before they participate. Introverts are easily overwhelmed by too much stimulation from social gatherings and engagement. They are more analytical before speaking.
Introversion is not the same as being shy or being a social outcast. Introverts prefer solitary activities over social ones, whereas shy people (who may be extraverts at heart) avoid social encounters out of fear, and the social outcast has little choice in the matter of his or her solitude.