iOS devices can be great music-making tools, but the inability to chain the audio signal path through multiple devices hampers usage a bit, especially live. Which is why this app thrills me. It also extends the viability of my 1st-gen iPad a bit, thanks to iOS 5 compatibility.
So basically, this app runs audio through other apps already on the iOS device in specified input, effect, or output slots. I'm seeing possibilities here as an effects processor for audio signal, more tonal options for soft synths, and just the ability to mess things up sound-wise.
It'll be a long week until I can get my hands on this.