Apparently at the Musikmesse show Numark was showing off this prototype iPod DJ mixer, but didn't want people to take photos. Unfortunately, they hadn't bothered to mention that until a few days after the show started, so German hip-hop site WebBeatz has some basic information. There's not a lot to know off hand, but it's sort of self-explanatory.

Analysis: Prototype Numark iPod DJ Mixer [CreateDigitalMusic via Engadget]