Amazon doesn't differentiate between the 3G or Wi-Fi only versions (although the $139 price point is cited as a factor), nor does the company provide any actual sales numbers. CEO Jeff Bezos also points towards the Pearl e-ink display and lightweight frame as contributing factors as well.
The Girl with the Dragon Tattoo was also praised as the most gifted and purchased Kindle e-book this Christmas.
Have you bought a third-generation Kindle this year? If so, has it lived up to your expectations?