Nintendo has release there demo of the new and updated Wii U at E3, it is mostly a new controller. The system will have support for HD video, older Wii games, and USB ports for new stuff. But the main thing they are building is a new controller that has a touch screen, camera, and motion sensors. It seems that it is mostly about having one of the new controllers and a bunch of Wii controllers that you should already have if you own a Wii. I’m sure if you want a second Wii U controller it will run around $100.
As for the games it looks like there are a lot of new ways to build games with or without the main system, and you can have 5 people playing in a demo game where they would chase down the 5th person with the new controller. Should be fun, but I still love PC gaming!