We've seen like a hundred (not really but it seems like it) 4K TVs at CES so far, but there are ultra high-def tablets, too. Panasonic just whipped one of these pixel-packed device at its keynote. And it's enormous.
The screen looks beautiful because, duh, double pixels. It looks super thin, runs Windows 8, and it comes with a stylus. But it's TWENTY INCHES. Twenty. You can't carry that comfortably. If it ever comes out, it'll be strictly for professional applications and ludicrously expensive. And because of its size, this crazy gadget is the tablet equivalent of a Publisher's Clearing House check.