As reported by Alex4D, who discovered this, Apple has acquired a movie notation patent. The world "acquired" is quite important because it means Apple had to pay to get it and it suggests that the company has actually plans to use it (as you know many companies patent everything "just in case"). This specific patent has been submitted to the US Patent Office in 2008, so many years have passed and as written in the description of the patent, the invention is directed toward providing annotating systems for audio/video clips. Here's some more info on it:
"In the movie, television, and audio/video production industry, directors often give instructions for the editing of audio/video clips, such as scenes in movies. Such instructions were previously written or typed independently of the video clip to which they referred. The technicians following the instructions had to determine the times in the clip to which a given instruction was meant to apply based on the typed or written notes themselves.
In order for the technicians to determine to which part of a clip an instruction referred, the written or typed instructions had to include the times within the clip that each instruction applied to. These notes had to be meticulous in order to avoid expensive editing mistakes. Taking careful notes of these times made annotating video clips more complicated, however, notes made without accurate time notations increased the chances of misunderstanding between the director and the technicians. Such misunderstandings lead to wasted time for both the technicians and directors.
Accordingly, a video annotating system that automatically keeps track of annotations for film clips and stores the information in an accessible way would be useful."
Alex3D reminds that in recent years OS X has had picture notation features, but what's interesting the examples in the documentation are based on Mac Finder and iMovie.
More info on the patent: [download PDF]