Amazon CEO Jeff Bezos took the stage today at Manhattan's Pace University to unveil the latest version of the company's popular line of Kindle ebook readers, the second such announcement in the space of a few months. The DX, the third model in the Kindle line, boasts a 9.7-inch screen, which is 2.5 times the size of Kindles 1 and 2 and designed to display periodicals and textbooks.

The display's electronic paper features 16 different shades of gray. The new model has native PDF support for documents that can be imported via USB. And PDF content can be read without scrolling, zooming or panning.

Also on the Kindle DX, as on the iPhone, auto-rotation automatically switches the device's display mode when it is flipped by the users. And the DX features 3G wireless access and 3.3GB of storage, which, according to the company, should hold roughly 3,500 books.

In keeping with the educational focus of the Kindle DX, Amazon has struck deals with three top textbook publishers, including Pearson, Wiley, and Cengage--the three make up 60 percent of the textbook market and include imprints such as Addison-Wesley, Allyn & Bacon, Benjamin Cummings, Longman & Prentice Hall (Pearson); Wadsworth, Brooks/Cole, Course Technology, Delmar, Heinle, Schirmer, South-Western (Cengage); and Wiley Higher Education.

Amazon will also be launching trial programs with a number of universities, including Arizona State University, Case Western Reserve University, Princeton University, Reed College, and Darden School of Business at the University of Virginia. The program will make the new device available to students in the fall.

Amazon has also launched deals with two top newspaper publishers, The New York Times Company and Washington Post Company, making subscription content from The New York Times, The Boston Globe, and The Washington Post available at a "reduced price."

The Amazon Kindle DX costs a lofty $489, compared with the Kindle 2's $359. The DX is available now for pre-order through Amazon's site and will go on sale this summer.