The iPad opens up fantastic opportunities for music creation and performance. We recently checked out Low End Theory's San Francisco debut. It was a great time, and I was stoked to see many of the artists and DJ's using iPads in their sets. Everything from triggering loops and beats, to controlling filters and other effects. The iPad was an extremely versitile tool in this setting and fit in perfectly with the turntables, laptops, and controllers setting on the table.
Here's a video from the event - iPad featured at 0:44 and 1:42