Mario Kart 8 will include some sort of “game chat” feature, according to a listing on the Wii U eShop. This term is a bit unclear, though some believe it relates to voice chat.
Originally, it was thought that Mario Kart 8 wouldn’t allow players to chat online. The discovery above, however, may prove otherwise.
Note that Nintendo has not announced voice chat for Mario Kart 8 at this time.