Since Amazon.com, Inc. released the Kindle 2 and Kindle iPhone application in the first quarter of 2009, net sales have risen 18 percent to $4.89 billion. In contrast, net sales were $4.13 billion during the first quarter of 2008.

Net income increased even more, the company announced today, jumping 24 percent in the first quarter of 2009, totaling $177 million. Book watchers should pay attention to second quarter results, as they will include any side-effects from the Twitter protests sparked by "a ham-fisted cataloging error."

In the release, Amazon CEO Jeff Bezos attributed the first quarter gains to the company's digital reader: "We're grateful and excited that Kindle sales have exceeded our most optimistic expectations."