https://i.ytimg.com/vi/FdtskdgYE08/hqdefault.jpg

Blendfile: http://blenderdiplom.com/en/tutorials/all-tutorials/560-tutorial-volumetric-logo-reveal-in-cycles.html

Since Blender 2.70, Cycles can render volumetrics. This tutorial shows how to use a homogeneous volume and anisotropy to great advantage.

source