The real question they're asking when they ask that is, "What have you done to overcome something you saw as a weakness?" So if your answer is that you're an introvert, then you have to say something like, "I tend to be pretty shy in person or on the phone, but I can write really, really well. So, I collaborated with my co-workers so that they were the ones making phone calls, and I was writing up the newsletter or their business correspondence, so the company was able to put its best face forward in all of its methods of correspondence."

I'm a job coach, and introversion's been the millstone around my neck, too. Then they switched my job so that I didn't have to contact random strangers, and the job got a lot easier. Also, because I have to help people get jobs, I've studied up a LOT on interview techniques.

(Hi, here from metaquotes)