A law suit has been filled by Cygnus Systems and accuses major companies like Adobe, Google, and Microsoft of having violated their patent by using thumbnails, which Cygnus claims it invented.

To this purpose they have patented a broad-base technology which states "a method and system for storing, navigating, and accessing files within an operating system through the use of a graphical thumbnail representing the video display of the active document within the active application."

If things turned into favour of Cygnus system then they will be world's richest then.
You can find actual story here:
http://www.electronista.com/articles/08/12/26/cygnus.vs.apple.etc/

interesting article and raises lots of questions with few answers until it goes to court.