EDIT: As many of you have pointed out, since the publication of this article Nintendo has revealed to GamesIndustry International that the menu accessed by the 'hacker' was in fact a mocked-up test menu and was not linked to the main Miiverse system.
Nintendo's official line is as follows:
It has come to our attention that some people were able to access a mock up menu on Miiverse following the launch of Wii U in the US. Please note that this was only a mock up menu and has now been removed and is not accessible.
Ah well, it was fun while it lasted.
ORIGINAL STORY: It's fair to say that the online side of Wii U hasn't gone exactly according to plan so far. First we were told that certain elements would be added after launch, and then many users were hit with a massive update as soon as they switched on their shiny new consoles - which took ages for some people to download. This morning we've also had the disappointing news that Nintendo Network IDs are linked to a single machine (for now).
It doesn't get any better, sadly. It has been revealed that a NeoGAF poster by the name of Trike accidentally managed to hack into the Wii U's admin hub, where he was able to uncover information relating to a series of new games:
I found out I could access the debug menu on Miiverse by hitting the "X" button on the gamepad while hovering over the exit button. I found an admin access list or something to that effect. I couldn't really do anything from there though. I could view different messages from a developer though. One mentioned that there would be big games coming out (announced?) on the 10th of December.
I went to another link that lead me to some test messages. I thought they were real when I found them, because they were posted 20 minutes ago from the time I accessed them. I could flag them for prohibited content, spoilers, and something else that I forget.
Then I went to a different link on the debug menu and it showed three different Miiverse subforums I could access that would be coming out on December 20th. I clicked on the "games for teens, kids and blah blah" (forgot the other two, I think family games was one of them?) and it lead to some sort of dispute between Timelord celebrities Tom Cruise and Brad Pitt. There were even more subforums for games specifically, including Yoshi's Island Wii U and Soul Hackers, and less specific ones like Metal Gear Solid and Resident Evils.
I don't know if I really could flag posts to be deleted or whatever, but I know I could not make myself an admin or delete admins. At least when I pressed the buttons nothing happened.
Nintendo has now apparently cut off Trike's access to the admin hub, but it makes you wonder just how secure the company's online infrastructure is if an end user - not a hacker - can inadvertently gain access.