"Here’s a little bit of background. Up until the Wii U, the device held all of the account information. Whether you played or your kids played or your partner played, it was all one set of data to the Wii. The same was true for DS and 3DS.
With Wii U, we’re going to have an account system. This means you’re going to create a Mii, as will all the other members of your family, and the behaviour for each Mii is going to be captured in an account. For example, if you’ve achieved a certain level in a game, that information will be unique to your Mii. Parental settings will be specific to each Mii.
This is critically important, because it means things like messaging and achievements and other key online functionality is tailored to you." -Reggie
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No details on what they will eventually be called but it's nice to have a confirmation.
While I'm not personally interested in them I still posted this because I know some people here that are.