A prequel to the classic Grease is currently in the works at Paramount.
The movie will be called Summer Loving, and it'll focus on the summer when Danny and Sandy first met. The events of the movie will be inspired by the song "Summer Nights", where Danny and Sandy tell their friends about the time they spent together.
John August, who wrote Tim Burton's Big Fish is set to write and direct. He also wrote 2 other movies coming this summer: the Aladdin remake and Scary Stories To Tell In The Dark. The movie is still in development, so casting will be announced at a later date.
The original Grease is still one of the top 5 highest grossing movie musicals of all time.