The Wii U dev kit is pretty much finalized, with the V5 version of the hardware in mass production and shipping to developers. VGLeaks got their hands on a new photo of an early version of the Wii U dev kit. Back then, the dev kits only supported the Wii Classic Controller via an adapter — The Wii U GamePad apparently wasn’t ready at that time. The latest version of the developer hardware, version 5, was reported to include new features such as dual GamePad support, video chat, facial recognition software, and multi-tasking.
For a more detailed photos of the hardware, check out the Wii U dev kit photos.