The New York Times is running a great story about the electronic future of sheet music. A body of patents starting in 1998 covers all the ideas now, including patents for "music annotation system for performance and composition of musical scores" and "a system and method for coordinating music display among players in an orchestra." Looks like writing and displaying music are now owned. The patent office couldn't find any prior art for some sort of "music annotation system"? There has also been music composition software on computers for quite some time. (See the related EFF Patent Busting Project).
An interesting aspect to this debate is the players fighting for patents in this niche market: a patent lawyer, Harry Connick, Jr., and a small, renegade electronics manufacturer.