Last Thursday morning, Apple Computer Inc. started selling an episode of the hit television series "Lost" through its iTunes Music Store for $1.99 after the show aired the night before on ABC. It marked the first time a popular show was made available for legal downloading over the Internet so quickly after its original airing.

With that, Apple may have helped open a Pandora's box for the media business. The Cupertino, Calif., company and its first TV partner -- Walt Disney Co., the parent of ABC -- have taken a potentially...