The new tablet driven mixer from Behringer announced at Namm 2014 is the X18. It has no dock, just a place to put your tablet - I say tablet and not iPad because, although it currently works with the iOS app for controlling the on-board DSP functions of the mixer, an Android app is expected sometime soon. Behringer are using the in built Wifi router to allow any thing to connect without the being tied to the ever changing connector.
Check the video and the Behringer site for more features.
Expected price $799
Designed for dedicated use with rekordbox dj professional performance application