Sony said Wednesday that it plans to launch the smallest digital TV set ever -- one that will be capable of displaying live television as well as recording shows for future play. The Bravia XDV-D500 features a 3-inch screen, a battery that can last 8 hours, and a 2 GB storage device that can hold up to ten hours of programs. The devices are not compatible with U.S. digital TV standards and therefore will be marketed only in Japan, which uses the OneSeg digital standard.