I saw this TEDTalks video about a year ago, and I still find the music and the message haunting – in a good way. I think it shows the very best of what can be done to explore new and innovative ways of using technology in ways that are both interactive and compelling within the arts. I really find this kind of collaboration fascinating because it stretches the idea of creation from being a personal or solo thing to a global endeavour.
By the way, if you enjoyed this, there are a couple more Virtual Choir videos now available from this composer/conductor.
Drama Cat: Drama Zone 
This is amazing! Have you thought about using this to preform a short play? Or a scene from a play? I think that it would be fun to try a dry run and record it to show your class an move to a live production. No sets required!
I’ll have to think about that and how that will work. It could make for an interesting piece of modernist theatre.