There is an A Tribe Called Quest album with a skit that almost always made me turn around to see who is talking behind me when listened to on headphones. AFAIK they used stereo microphones on a mannequin to achieve this effect. I don't know what my point is but I guess it's a bit surprising that it took so long for this to enter the mainstream as we've certainly had the ability to do his with minimal extra processing for quite some time now.