The new record is called Unvarnished and will release on October 1st. It's the first new music from Jett since 2006. According to Billboard, the album will include songs about the death of Jett's parents and Hurricane Sandy.
It is unclear exactly what Grohl is doing on the album, but he has contributed drums to various projects before. Grohl notably played drums on the latest Queens of the Stone Age album, ...Like Clockwork.