UPDATE: Nintendo has confirmed Nintendo Network ID replaces Friend Codes for the Wii U.
A statement provided to Eurogamer reads: "Friend Codes will indeed not be used on Wii U. Players can use alphanumeric characters to create their Nintendo Network ID, this is not an automatically generated number."
ORIGINAL STORY: Nintendo will allow you to create 12 user accounts per Wii U. These profiles are tied to your game saves, settings, browser bookmarks and play history, Nintendo has announced.
But eShop purchases can be played by any user on the system, company boss Satoru Iwata explained in today's Nintendo Direct conference for Japanese gamers (translated by NeoGAF).
Boot up the Wii U and your TV screen will be entirely devoted to Nintendo's new Miiverse social platform, which shows information on new games and details what your friends are playing.
The GamePad will house a more standard menu, which includes icons to launch downloaded content and the currently loaded game disc. It looks very similar to the current 3DS interface.
You'll need a Nintendo Network ID to use online functions such as video chat (presumably the details of your eShop account if you've used a 3DS).
Once again Nintendo confirmed that you'll be able to interact with the Network via other Nintendo systems, PCs and smartphone apps. The company previously announced a plan to make the 3DS eShop accessible via these devices.
Most importantly of all, pausing gameplay to access the Wii U menu uses the same sound as pressing the Home button on the current Wii. Da-dah!