This is one of the slickest iPhone 4 videos I've seen in a long time. A guitarist (justkylevids on YouTube) apparently wondered what it was like being inside his guitar while playing, so he dropped his iPhone 4 in with the video camera running and captured this incredible video.
The effect you see is mesmerizing, but not really representative of the way that guitar strings actually oscillate. Instead, it's another example of how the iPhone 4's rolling shutter can create some interesting photos and video. Still, it's fun to watch.