That was taken on an iPhone. It happens in camera phones not because of a physical shutter, but because the entire frame isn't captured at once.
http://farm4.static.flickr.com/3158/2421813332_3c36b3b808.jp...
http://farm4.static.flickr.com/3187/2421813434_dbdc309901_b....
The sensor will transmit the picture, but the iPhone is not ready to process all of it. So the next burst is processed later but is used for the same image.