"For those of you asking: Shake is (was?) a video/film compositing application. It can be used to perform blue/green screening tasks, more complex rotoscoping (or tracing footage) work, and compositing layers of video/film footage into one scene. Shake was used by some very well-respected visual effects houses such as Weta Digital (who did virtually all the visual effects in the "Lord of the Rings" films as well as Peter Jackson's remake of "King Kong"). It completely baffles me why Apple would choose to abandon this application just as it seemed to be picking up steam in the industry. People I know of who use it regularly swear by it. Strange move, Apple." - davidjtate