The Kindle app that lets users to read their favorite eBooks on an easy, mobile interface has now become available in the new Mac App Store. Although Kindle is not new for Mac, the app for Mac is a new product, and is already topping the charts.

Apple’s iBooks has limited usability, just for iPhone and iPad. This is another reason that Amazon’s Kindle app remains on top as it lets you read eBooks on Kindle, iOS, Android, Windows Phone 7, Windows, Mac and BlackBerry devices. This shows the non-seriousness of Apple towards eBooks, that was not expected at all. In fact, we all hoped to see their software already available on all of their operating systems.

Amazon’s Kindle has made so many accomplishments last year and established as a highly popular device.  And its regular schedule of updates has proven a successful tactic for the Kindle app.  Some of its more recent updates include periodicals, a Kindle Web update and a Windows Phone 7 release.  As an evidence of its platformed success, let’s just recall Kindle beats “Harry Potter and the Deathly Hallows” as the bestselling product in Amazon’s history.

We’re grateful to the millions of customers who have made the all-new Kindle the bestselling product in the history of Amazon — surpassing Harry Potter 7,” said Jeff Bezos, Amazon.com founder and CEO. “We’re seeing that many of the people who are buying Kindles also own an LCD tablet. Customers report using their LCD tablets for games, movies, and web browsing and their Kindles for reading sessions.”

On the other hand, Apple also opened its Mac App Store to sell apps in order to fulfill its plans of expanding apps and their functions. One can search apps by category, be it under games, productivity, music etc. or just by using the search.