I liked this little gem in the Ars piece about Loren Brichter and Tweetie development.
He did say, however, that that he looks forward to the day he can develop code on the iPad and ditch his Mac for creating software. "If you break the idea that we have to use software keyboards the traditional way, there's so much potential for insanely fast programming," Brichter said. "Think about keyboard buttons becoming whole variable names. You could become so efficient while programming!"
The common iPad thread is that it's a better content consumption machine than a content creation machine. There's a slate of apps in the store now for music creation (keyboard + drum machine + sequencer variations) with customized UIs that borrow heavily from physical devices. (And at some point we'll see iMovie for iPad, right?) I'd love to see someone build a dedicated environment for Processing on the iPad. Programmable "keyboard" + eye candy = yum.