Smule develops iPhone apps. These include Ocarina, a virtual instrument that takes advantage of many of the device's input methods: the touch screen to cover virtual holes, the microphone as a breath controller, and the accelerometer to control timbre by tilting the phone. You can also hear what other people around the world are playing and rate it! And then, of course, there is "Zeldarian mode."

Not having an iPhone, I haven't had a chance to try this, and even the developers seem to acknowledge that it can be finicky, but then again, so can real instruments. Even so, it's pretty compelling that virtual instruments might be made so expressive. It's always been a peeve of mine that it's so laborious to put the same level of nuance into an electronically produced sound that would be natural if not effortless on a guitar or any physical instrument. One common but perhaps unfortunate solution to this is randomization, a.k.a humanization, a route taken by a few Audio Damage products.

I have to say though, I'm not sure what I will think the first time I go to a concert and see someone pull out their phone and start 'playing' it.

Smule is run by the creators of ChucK, a neat audio programming language that I have played with from time to time.