Nvidia just surprised a whole bunch of people by announcing, of all things, a dedicated gaming handheld during the company's CES press conference.
Based on the new Tegra 4 mobile chip, also announced at the show, it's code-named Nvidia Shield. There are 5-10 hours of battery life, and it's based on a clamshell design, sort of like a DS (only without the bottom screen).
Running on Android (they say "pure Android", so hopefully no Nvidia skin), it's got a MicroSD slot, micro USB and HDMI output (which supports 4K output so long as your display does). The Shield's 5" screen is a touchscreen, and is capable of 720p display at 294dpi (they're calling it a "retinal display").
A small shield on the back of the top screen is removable and customisable. Below you'll see a size comparison, facing the Shield off against an Xbox 360 pad and a Wii U Controller.