http://david-heron.me.uk/blog/2007/04/08/virtual-barbershop
Make sure you use headphones.
They probably used something like this Neumann microphone (http://www.neumann.com/?lang=en&id=current_microphones&cid=ku100_description). They use it sometimes when they record concerts to make it sound really great in headphones, it's too bad they don't work very well for normal speakers.
Here's a couple more.
http://david-heron.me.uk/blog/2007/04/26/holophonic-sound/
http://david-heron.me.uk/blog/2007/04/27/more-3d-sound/