The first Wii U update will be available to consumers when the system launches on November 18th in North America. The Wii U update will add Miiverse, Wii U Chat, Nintendo TVii and the Wii U eShop. Presumably these features are only available via a system update so that gaming press don’t get to try out the features on their pre-release console’s before Nintendo has talked about what they offer.
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Source:
http://mynintendonews.com/2012/11/06/wii-u-will-have-day-one-update-which-includes-many-features/