This spring (they hope by May) there will be a various artist compilation that is inspired by the Sacred Harp documentary, Awake, My Soul & Help Me to Sing. The Innocence Mission contributed a song which we are told is "just staggering." Other contributors include Sufjan Stevens, Jim Lauderdale, Led Zeppelin's John Paul Jones, Woven Hand. You can hear DEE's song "Consecration" which has been playing on his myspace page for the past few months.
Here's a Time magazine article about Sacred Harp, and there's also Fasola.org which has more info on shape note singing courtesy of Mike Bitts.