In October, the Brooklyn rock quartet Atomic Tom posted a video on YouTube of the band performing their song "Take Me Out" on the B train in New York City, using nothing but musical instrument apps on their iPhones.
The video got two million views in the first week, and the single rocketed its way on to iTunes top 100 chart.
Here's the video. The guitar app is iShred. And they are probably also using Virtuoso, Drum Meister, Pocket Guitar, Bassist, and Von Bruno microphone.