Wizdom Music's latest app is finally here! Tachyon is a Universal graphical-morphing-sampler app.
You see a graphic representation of an instrument, and you can morph that into another instrument... or power tool. Notes are played along the X axis similar to MorphWiz, complete with selectable scales, but your finger placement along the Y axis controls the morphing.
That may be an introductory price, most of the other Wizdom apps are $9.99!
Here is Jordan Rudess' personal tour of the features.
Tachyon is designed to let you graphically morph between two sounds. The iPad surface is used as a multitouch XY interface, where the x-axis controls pitch and the y-axis controls the blend of two different sounds.