It is Nintendo's next home console.  It will support high def and the screen is able to show its own view.  This screen can serve multiple purposes, either shrink the regular screen down, show a portion of the screen on the TV, or show something completely different, depending on what is needed.  Here is some uses that are of value:

* Have a separate inventory screen from what is on the TV, so you don't have to switch.

* For a driving game, treat it as a rear view mirror.

* For an American football game, select plays off the top screen.

* If someone comes in the room to take over the TV, you can still play.

There are other options to, that I can't even begin to process that feel awesome to me.

I think this is a brilliant idea. You can really mix it up. It would be really awesome if you could have 4 tablets at once. Think, though, it might be one only plus 4 wiimotes.

Considering EA was at the presentation, and talked about doing what they do normally off the screen, I see it would be more than just one U controller to do things.  I see for American football, that the playcalling for both players would be off screen. Also the split screen thing indicated that you could have four different views via the controller.