According to http://www.modmyifone.com/forums/showthread.php?t=89701 there is a new version of Pianist out. Pianist is a virtual Piano application for the iPhone.
Features:
A complete four octave keyboard
Multi-touch. Up to 5 keys can be pressed at once allowing complex chords.
Sounds like a real piano with realistic piano multi-samples.
Animated piano keys react to your touch.
Play along to all your MP3s.
On-screen keyboard navigation allows you to easily move up and down by octaves or “part octaves” (ie. left-most key is a C or an F).