More details
From the new listing on Amazon.com:
Slim: Just over 1/3 of an inch, as thin as most magazines
Carry Your Library: Holds up to 3,500 books, periodicals, and documents
Beautiful Large Display: 9.7" diagonal e-ink screen reads like real paper; boasts 16 shades of gray for clear text and sharp images
Auto-Rotating Screen: Display auto-rotates from portrait to landscape as you turn the device so you can view full-width maps, graphs, tables, and Web pages
Built-In PDF Reader: Native PDF support allows you to carry and read all of your personal and professional documents on the go
Wireless: 3G wireless lets you download books right from your Kindle DX, anytime, anywhere; no monthly fees, no annual contracts, and no hunting for Wi-Fi hotspots
Books In Under 60 Seconds: You get free wireless delivery of books in less than 60 seconds; no PC required
Long Battery Life: Read for days without recharging
Read-to-Me: With the text-to-speech feature, Kindle DX can read newspapers, magazines, blogs, and books out loud to you, unless the book's rights holder made the feature unavailable
Big Selection, Low Prices: Over 275,000 books; New York Times Best Sellers and New Releases are only $9.99, unless marked otherwise
More Than Books: U.S. and international newspapers including the New York Times and Wall Street Journal, magazines including The New Yorker and Time, plus popular blogs, all auto-delivered wirelessly