I've been saying it for almost three years now...the iOS app ecosystem has truly changed the music industry. Nearly everything you needed to do in order to be a working musician you could do in some way with your iPhone/iPod/iPad.
And that was before the core MIDI spec was rolled out.
Now, with the ability to hook up MIDI peripherals, iOS-powered instruments are impacting music performance too, as ION's new Guitar Apprentice shows in the video above. It cuts out the need for a MIDI breakout box, and gives guitarists a unique way to record and perform for relatively little money ($99).