Nintendo has filed a patent for a portable gaming device that allows the user to customize the handheld's controls to their liking. It's worth noting that the patent directly references mobile phones in addition to dedicated gaming hardware.
The patent was first discovered by NeoGAF user Disorientator, and bears the following description:
An information processing device such as a game machine or a mobile phone is provided with an operation unit with one or more buttons, switches or the like for accepting operation by a user. A game machine, for example, is provided with a cross key, an analog stick, an operational push button or the like, to accept operation concerning a movement or an action of a character in a game, or operation concerning various games such as operation for selecting a menu. Furthermore, a mobile phone is, for example, provided with an operational push button on which a number, a letter or the like is written, and with a directional key or an analog stick for, e.g., four or eight directions, to accept operation concerning speaking, electronic mail transmission/reception or the like.
There's no doubt that Nintendo is already working on new gaming hardware, but we have yet to hear specifically what the company's plans are for the future. Will we hear something at this year's E3? It may be a little early for an official reveal, but with the Big N you never know!