Analyst Ming-Chi Kuo of Concord Equity Research says that Amazon produced 1.6 million Kindles in December, matching the production of Apple's iPads during the month.

The catch: Apple apparently ramped production down from 2.1 million in anticipation of the iPad 2, which could be announced as early as January, according to AppleInsider. Kuo formerly served as a reporter for Taiwan's Digitimes, a source of many recent rumors about the iPad 2 and Apple's iPhone production plans.

Kuo also estimates that Amazon has sold 5.4 million Kindles since releasing the Kindle 3 and lowering prices across the product line in August. Amazon has called the Kindle 3, released in October, its best selling product ever, but has refused to disclose exact sales numbers. An earlier report from Bloomberg estimated that Amazon will sell more than 8 million Kindles in 2010.

The iPad can serve as an electronic book reader, but Amazon CEO Jeff Bezos recently claimed that many consumers buy both devices: the Kindle for reading books, the iPads for games, movies, and Web browsing.