This video, found on Google Video, shows us a time lapse painting of a Picasso work. In 1955, French director, Henri-Georges Clouzot filmed Pablo Picasso as he painted 20 piece. This became the film The Mystery of Picasso.

This is one of the paintings from the film, taken from start to finish.
http://video.google.com/videoplay?docid=-344110265961797058