Miyamoto has finally confirmed production of a HD Zelda, in an interview with Kotaku:
This is an HD system, our first HD system, and we want to create a real HD Zelda game for it. You will see a lot of these in-depth and deep experiences in terms of visual style. You will also see some play styles that are fun and interesting because of the play structure.
Given the E3 screenshot above (see the full pic here), this confirmation isn't too surprising, but it should convince Nintendo fans to put yet another finger over their wallets for the Wii U.
The screenshot comes from a tech demo at E3 showing pre-rendered footage of Link battling a giant spider in full 1080p. Though the player didn't control Link directly, the player could select different camera angles and lighting differences between day and night with a simple tap on the Wii U. The game could also stream to the Wii U unit itself and, with headphones hooked into the jack on top of the controller, it provides a private session where your dad can watch football on the TV simultaneously.