You're looking at the work of Nicholas Chen, a PhD student up at the University of Maryland. He's been working on the concept of cooperative single screen ereaders for a few years now. As you can see from the video, he's pulled off some rather interesting features.
He has 3 ereaders there, not one. They're designed to work together so you can send a document (or even a single page) from one screen to the next. They're not connected physically and the only things keeping the 2 units pictured above together are magnets.
The video is after the break.