"To promote HBO's "Entourage," FreeCar Media has built LCD screens — the kind used in laptop computers and other portable devices — into the front of T-shirts that will play clips from the show. (The battery-powered shirts project high-quality picture and sound, and weigh in at just 2.5 pounds.)" -- NY Post (free registration)
Not terribly new. I remember seeing it done last year by a company called T-Shirt TV.