Native Instruments has released the app Traktor DJ for iPad 2 and higher. It is not Traktor Pro, but it can be fully synchronized with the DJ software for PC and Mac.
You get two decks, two channels with 3 band eq and a filter section, eight Traktor effects (one per channel), waveform manipulation, looping, scratching and cueing.
Traktor DJ costs € 18 and is now available in the App Store. In the videos below you can see a demonstration of this app, including the DJ Richie Hawtin.