Onoko has released Pad MIDI, a free app for iOS 3.1 or higher.
Pad MIDI provides several MIDI pads for iPhone/iPad.
Pad MIDI features
- Supports native Mac OS Network MIDI (Core MIDI).
- 16 assignable / renameable MIDI pads.
- Full 88 key piano.
- Selectable MIDI channel and velocity.
Pad MIDI is available to download from iTunes at no cost.
More information: Pad MIDI