A final channel lineup is still being developed, but AT&T says it will include lots of family-friendly entertainment, including Disney Channel, Disney XD, Discovery Kids, Animal Planet, Nickelodeon, Cartoon Network Mobile, USA, COMEDY CENTRAL, MSNBC, CNN Mobile Live and CNBC.

The system requires installation of a 3-pound, 11.3-by-10.3-by-4.3-inch antenna on the roof of your vehicle. AT&T describes this as "not particularly noticeable," but I'd take that observation with a grain of salt: Check out the rooftop image, above.

AT&T says its technology addresses shortcomings of other in-car entertainment systems. For example, the company says, its breakthrough buffering technology keeps the show going even when you're under a tunnel or other line-of-site obstacle.

Avis and Budget car rental services have announced plans to make the Cruisecast service available in rental cars at some locations for $9 a day or $63 a week.