The Wii U is still a bit of an enigma, despite being unveiled at E3 2011, Mario, Zelda, and minigames in tow. Regardless, the United States Patent and Trademark Office has some pretty loose lips. The Wii U's tablet-screen controller was recently filed away in what one can only assume is the setting of the next National Treasure movie.
The Wii U controller comes with a built-in lithium ion rechargeable battery, an IR port, a speaker, and a microphone. There's a gyro sensor and acceleration sensor at play inside the controller. In addition to all of these pretty-much-expected features, the Wii U's controller will also come with a Magnetometer which totally sounds like a word I just made up.
The filed patent details the use of a Wii remote in conjunction with the tablet screen, as seen in the image below. At such a large size and with so many buttons, you'd think the tablet controller would be difficult and uncomfortable to hold, but you'd be wrong. In my experience, the Wii U's tablet was light, but firm, and rested snugly in my palms. Of course, I have basketball-player sized hands so take that with a grain of salt.