According to a reliable Japanese retailer who emailed WiiUDaily, the launch date for the Wii U has been pegged for November 18th, 2012 for North America.
The Wii U is expected to be released a week after the aforementioned date in Japan although a PAL release date was not mentioned on the report.
Nintendo have yet to officially announce a release date for the Wii U but many people who read the report believe this to be true. After all, the original Wii console was released around the same time back in 2006 to great success.