Korg announced a new USB MIDI controller series that looks like it would be ideal for Ableton DJs. There are three different controllers in the "nanoSeries". One is a keyboard, one is a mixer, and one is a set of touch pads.
A 25-note, velocity-sensitive keyboard. I use a keyboard kind of like this (an Edirol PC-1) for triggering loops in Ableton and for cueing tracks in Traktor/Serrato/Whatever.
12 drum pads and a touch-sensitive X/Y pad.
9 faders, 9 knobs, 18 switches. Great for a mobile digital DJ.
All three controllers are USB bus-powered and do not require a power brick. Just plug the controller in, plug in your bus-powered multi-channel audio interface box, launch Ableton, and you're making music. With stuff that will fit in a backpack, and with only one cord plugged into a wall outlet.
The only official information from Korg so far is in Japanese. I'll post a link to an English site as soon as Korg updates the English web site. Pricing information hasn't been announced.