Well guys, as there is already a thread about Vray, I would like to share with you the articles,which I found very useful to understand individual function of this engine, maybe you have already found and read it, but there they are:
Antialiasing and Color mapping
Indirect illumination
Irradiance Map
Light Cache
GI Engines Choice
DMC Sampler
Raycasting
May the good times and treasures of the present become the golden memories of tomorrow.