It seems that the admin dashboard for the Wii U's Miiverse was briefly accessible by one and all, as one NeoGAF user discovered while he was trying to set up his Nintendo Network friends list (protip: you have to actually go to the friends list app, accessible from the Home menu). While "messing around in Miiverse," NeoGAF's Trike found his way into a secret debug menu that included access to a prototype, all-Japanese Miiverse and a list of admins.
Further exploration revealed a few facts which may or may not be true, given the mock-up nature of this prototype Miiverse. New Communities for the Wii U's game-specific social network were spotted, for "Metal Gear Solid," "Resident Evils," "Soul Hackers," and, excitingly, "Yoshi's Land Wii U." Nintendo reportedly fixed the backend exploit quickly, reiterating in a public statement that what people saw was, in fact, just a "mock-up."