The OpenGL team wrote in with this announcement:
The GL2 Workgroup has approved the draft version (865KB pdf) of the OpenGL Shading Language (glslang).
The recent trend in graphics hardware has been to replace fixed functionality with programmability in areas that have grown exceedingly complex (e.g., vertex processing and fragment processing). The OpenGL Shading Language has been designed to allow application programmers to express the processing that occurs at those programmable points of the OpenGL pipeline. Independently compilable units that are written in this language are called shaders. A program is a set of shaders that are compiled and linked together.
This current (nearly complete) draft of glslang is being released for comment. Discussions are welcome at the forum Suggestions for the next release of OpenGL.