It's essentially a Nintendo DS hooked up to two Tablet PC screens, using an FPGA in between to do some translation magic. Pen input from the Tablet PC screens is sent back to the DS. It can also dump screenshots to a PC via serial port. The device cost its maker about $600 to make and includes two Gateway M275 screens, LVDS modules (Advantech PCM-205), Digilent S3BOARD a Nintendo DS and a Wacom pen. Yeah, that's a lot of geek talk, but check out how cool it is.
For additional pics, check out the maker's website.