Just a cloud of up to 80000 particles dancing along the curves of a turbulence field, reflecting their own light. Nothing really complicate (but expect some long rendering). I used the particle info node in Cycles to let the material of each particle change from emission to glossy after their instantiation. No post-processing beyond some glow and DOF.
I used 400 samples for the cropped snapshot but 200 is enough. Check the 1080p video at:
http://www.youtube.com/watch?v=jourxsLnlGQ
I guess it should be possible to drive the movements of the emitters with sound. Not sure about the result tho, the particle emitters must follow a smooth path or the cloud may become rather chaotic. I must say I haven't explored much the sound drive features of Blender... but I feel a sudden urge to do so. At least, to drive the colors of the particles should give... a more colorful result.
If nothing else, you could modify the materials of the particle system so the halo effect would get more intense on the beats of the song. That's probably what you meant, but yea, lol.
good work. can you make this sound driven as well?