Perhaps this e-book thing is taking off after all: Kindle books are now outselling Amazon's hardcover books in the US. The company announced Monday that it has sold 143 Kindle books per 100 hardcover books over the last three months (it has sold 180 Kindle books per 100 hardcovers over the last month), and that's including the sales of hardcover books where there is no Kindle edition.

Amazon also said that Kindle hardware sales had tripled since the company lowered the price from $259 to $189 just one month ago. Amazon CEO Jeff Bezos said that lowering the price was the tipping point to accelerate sales and eventually eclipse hardcovers, even though sales of hardcovers continue to grow. He added that this news is "astonishing when you consider that we've been selling hardcover books for 15 years, and Kindle books for 33 months."

Amazon also recently lowered the price and gave a makeover to its Kindle DX, which now sports a higher-contrast e-ink screen and a graphite bezel for $379. This is nice and all for those who value the larger screen, but it's clear that the majority of potential e-book customers prefer the smaller and cheaper version of the Kindle.

What else is clear is the fact that users apparently aren't as attached to dead tree books as some e-book critics thought. Paperbacks are surely still selling at sky-high rates, but the appeal of having a "stack" of books crammed into one, slim device is certainly winning over customers.