The Mobile DTV standard - officially ATSC-M/H (mobile/handheld) - will be finalized later this year. You'll be able to buy the first portable digital TV products around Thanksgiving/Christmas this year, but LG already has working prototypes of Mobile TV gadgets to come.
Mobile DTV is essentially simulcasts of live local broadcasts that you'll be able to receive on a number of gadgets, as well as on older devices via a tuner dongle. The broadcasts will be digitally perfect even when riding in a car or train. Most local stations will probably multicast several different channels, and there'll also be video-on-demand. Right now, 63 stations have committed to broadcast Mobile DTV in 22 markets, covering 35 percent of U.S. TV households.
Pictured above is a portable TV. Arrayed below are a cellphone, an MP3 player, a PC with a Mobile DTV dongle and a portable DVD player, all receiving live local digital TV programing. There's also a Kenwood back seat display attached to a tuner box that can be connected to an in-car AVN (audio/video/navigation) system.