One of my favorite pieces at MOMA (New York's Museum of Modern Art) is the Forty Part Motet installation by artist Janet Cardiff. Forty individual speakers have been arranged around a large, acoustically reverberant room, with each speaker representing the voice of one singer. The speakers play a looped performance of Thomas Tallis' Spem in alium motet for forty voices. The effect is pretty phenomenal -- you can sit in the center of the room and hear the amazing acoustical conglomeration of the forty voices (singing forty different parts), or you can walk amongst the speakers and listen to the individual voices.
So, not simply the recording of a choral performance, but a digitally replicated choir. While the music is beautiful and the choir superb, the true art form of this exhibit is the SPACE. Although a simple room, it is the room's acoustic that blends the sound into a choral whole, rather than a digital recording effect.
"An Overgrown Path" describes a different installation of the same performance piece, including a nice description of the work by the artist.