On what would have been Marvin Gaye’s 80th birthday, the U.S. Postal Service today honored the music legend with the dedication of a new commemorative Forever stamp during a first-day-of-issue ceremony at the Greek Theatre, where he once performed. Gaye was one of the most influential music performers of his generation. He helped shape the buoyant sound of the Motown record label in the 1960s and broaden the scope of R&B music in the 1970s. Released in 1971, his expansive masterwork, “What’s Going On,” is widely considered one of the greatest recordings in the history of American popular music.