Check out these cell-phone-camera shots of airplane propellors, victim to an effect known as "rolling shutter."
What gives? As Flickr user Jason Mullins explains,
[I shot this with] an iPhone 4, and the scanning typically goes from top left to bottom right so moving objects lean to the left. Essentially any electronic shutter camera (i.e. not an SLR like mechanical shutter) will give these effects. Wikipedia has some good articles here: en.wikipedia.org/wiki/Rolling_shutter
For those who want to try this out, just point your simple electronic shutter camera at an object moving parallel to you, preferably fast, and take the photo. The faster the relative speed between you, the more the distortion. Rotating objects go really weird!