Akai has launched a new Syncstation49 keyboard that sports a built in iPad dock as well. The dock is designed specifically to be used with keyboard. It features a 49 full size keyboard with velocity sensitive keys, modulation wheels, 0.25 inch outputs and 9 backlit MPC drum pads.
You will also find a USB port for connecting it to a PC or Mac. The keyboard can also functions as a traditional MIDI controller. To use the keyboard with the iPad, you will also have to install the accompanying iPad app that offers direct in-app MIDI recording. Pricing information is not available at the moment.