GL Shading Language 1.30 is the GLSL version for OpenGL 3.0 compliance. The AMD "R600g" driver has already supported beyond GLSL 1.30 while the RadeonSI driver for the very recent AMD GPUs has been left to mature for the year and a half since the hardware's debut.
The RadeonSI driver is focusing a lot upon the AMD LLVM back-end, since it's also necessary for OpenCL support. With the new set of six patches by Michel Dänzer, he believes GLSL 1.30 support should be rounded out.
Michel believes the patches may need some refinements but he's hoping to see the patches merged into LLVM ahead of the LLVM 3.3 release in June.
These new RadeonSI LLVM patches are currently on the Mesa-dev mailing list.