Cross Platform Shaders in 2012

Update: Cross Platform Shaders in 2014. Since about 2002 to 2009 the de facto shader language for games was HLSL. Everyone on PCs was targeting Windows through Direct3D, Xbox 360 uses HLSL as well, and Playstation 3 uses Cg, which for all practical purposes is the same as HLSL. There were very few people targeting Mac OS X or Linux, or using OpenGL on Windows. One shader language ruled the world, and everything was rosy.