The cold water vs. warm water is a rather interesting thing. Do you know that if you fill your ice trays with hot water, they freeze faster than if you fill them with cold water? It's all in the speed of the electrons moving around and what not. Fascinating stuff. Same thing with the thaw, hot water will cool down faster and cause the meat not to thaw out as evenly due to drastic swings in activity but, the cold water while cold to us, is still warmer than the icy butt and therefore causes the thaw to occur at a nice even rate.
Or atleast, that's the way I understand it.