We just published our review of the Wii U, but we didn't crack the console open to peer under the hood. iFixit did, though, and it has published a look at its usual stellar job of disassembling the console down to its component pieces and explaining what they do.
The most interesting part of the teardown, frankly, is the look inside the Wii U's GamePad. The controller is essentially its own console packed with components. In addition to a gyroscope and a touchscreen, the controller also houses an NFC module and antenna, though its functionality doesn't appear to be used by any of the launch titles. iFixit speculates that NFC could be used in the future to facilitate saved-game and character loading.
The Wii U itself sports a trio of wireless modules, including a Broadcom Bluetooth chip. One of the modules is used exclusively to communicate with the GamePad, enabling the smooth and lag-free screen mirroring observed by our gaming editor Kyle Orland. The teardown also exposes the system's AMD Radeon GPU and IBM Power-based multicore processor, both of which are marked improvements over the older Wii's downright anemic CPU and GPU.