The below is from a press release that SEGA sent out for Sonic & All-Stars Racing Transformed:

Sonic & All-Stars Racing Transformed will be available on the Xbox 360, PlayStation 3, PlayStation Vita, the Nintendo 3DS, Nintendo’s Wii U, and Windows PC Digital Download this November.

This press release is stating that the Nintendo Wii U version of Sonic & All-Stars Racing Transformed will be coming out in November, so that would mean the Wii U would be out in November or earlier than that. November is the month people are expecting the Wii U to launch in, but it may be that Sega unintentionally confirmed the launch month for the Wii U.