That may be about four times the number sold last year, but if you follow this sort of thing at all you won't be surprised. I've owned every model of the device over the years, and this third iteration of the smaller model is damn near perfect.
Upon seeing mine, my girlfriend wanted one immediately (and so I got her one). Now, months later, her sister and both parents each have a Kindle 3. When it comes to long-form reading, there is no better electronic solution.