The first Amazon Kindle was released more than three years ago, and for whatever reason, Amazon still won't share exact sales figures concerning the device. But this morning, the company did see fit to disclose one important fact: the third-generation Kindle has become the bestselling product in Amazon's history. To put that in perspective: "Harry Potter and the Deathly Hallows" previously held the title, and that franchise has had national reading programs, Halloween tie-ins, a string of hit movies, and even a theme park help boost its sales.