Any music with rhythm acts as a form of entrainment.
All music, in fact all sensory stimulation, creates some sort of effect upon brainwave patterns.
There was some research on the so-called "Mozart effect" which showed that in some cases listening to Mozart could create a brief increase in IQ.
I contend that most of this "psychoacoustic audio technology" is gimmicky. "Brainwave entrainment" is a gimmicky name for something very simple that has been around forever.
[This message has been edited by babayada (edited November 30, 2004).]