The Washington Post linked to a document that they received that includes the current plans from the "Citizen's Stamp Advisory Committee." On that list are numerous upcoming commemorative stamps saluting music icons from pop, rock, R&B and country.
There is a bit of confusion over the status of an upcoming Elvis Presley release. According to the article in the Post, the post office will be reissuing the Presley stamp from 1993 which is the best selling stamp in the country's history; however, the leaked list shows it as a new issue and not in the reprint column. We'll have to wait until next year to see whether we get 50's Elvis, 70's Elvis or something in-between.