http://www.youtube.com/watch?v=Ufc8DemQSFk

Saitara (App Store link) has released three Wireless MIDI apps for the iPhone:

• AC-7 DAW Control Surface – The AC-7 DAW Control Surface provides wireless remote control of your DAW software over a wifi network. The communication is two-way, meaning the DAW is controlled by the AC-7 while also sending real-time updates back to the device.
• AK-7 Midi Keyboard – It has no sounds onboard, rather it is used to play software instruments in Garageband, Logic etc. It requires the free DSMI Server software to be installed on your computer, and a wireless network.
• The AG-7 Midi Guitar – a tool for performing and recording guitar parts. MIDI information is streamed over your WiFI network to your recording software.

See more demos below.

http://www.youtube.com/watch?v=J-37teyCJtE

AG-7 Midi Guitar for iPhone and iPod Touch

http://www.youtube.com/watch?v=zBjvKkw5YHY

iPhone AC-7 DAW Control Surface – Demo with Logic