In a roundtable discussion posted on Nintendo's website last night, president Satoru Iwata and the team behind Nintendo Land revealed some interesting tidbits about the Wii U development process, as well as the hilariously constructed GamePad prototype you see above. Part of the ongoing Iwata Asks series, the talk quickly turned to the topic of simultaneous software and hardware development.
Nintendo Land directors Takayuki Shimamura and Yoshikazu Yamashita (who were also behind Wii Sports and Wii Sports Resort) were apparently tasked with developing ideas for the game before the details of the Wii U were even locked down, though Nintendo was set on multiple screen gaming.
In fact, one of their first ideas was a screen mounted on the end of a Wii Zapper with an embedded gyro sensor—while that model obviously never made it to market, Iwata claims it did result in Miyamoto demanding the 11th hour addition of a similar sensor to the 3DS.
Eventually they stumbled on what would be the rough form factor for what we now call the Wii U GamePad, constructing a prototype "stuck together by double-sided tape" which they used with "two Wii consoles to run simulations for Wii U." You can read the rest of the Iwata Asks for more insight on the mindset behind Wii U and the gestation of Nintendo Land. Or you could just look at that picture some more and shake your head, slowly.