Amazon's announced its quarterly results for Q4 2009, and they're pretty good! Lots of dollars, in this here document. But tucked somewhere between the currency symbols and financial jargon was a choice quote from Jeff Bezos, about a little secret he's been keeping:

Millions of people now own Kindles, and Kindle owners read, a lot. When we have both editions, we sell 6 Kindle books for every 10 physical books.

Amazon doesn't provide Kindle sales figures. In fact, Amazon doesn't even provide a Kindle sales ballpark, so "millions" is the most specific information we've ever seen about how well their ebook reader, and in turn the ebook reader as a product category, is doing. The answer? Not terribly, but not necessarily very well. Baby steps!

Assuming their app runs on the iPad, which seems safe, those already impressive book sales rates could go through the roof. [Amazon via Ina Fried]