Peter Kirn at CDM did a roundup of already available, and soon to come,  iPad Music apps.

The bigger picture, indeed: by blowing up the screen of the iPhone to tablet proportions, the iPad has become a lightning rod for discussions about the future of computing. It has also left interface designers with a challenge: what should interfaces look like? Can you simplify designs, as on the iPhone, but also make use of a screen size closer to what’s available on desktop computers? Those questions are especially potent when applied to making this new generation of devices expressive in music.

Check out the whole article here.