GLSL 1.40 was part of the OpenGL 3.1 specification while GLSL 3.30 was introduced with OpenGL 3.3. In a very simple Git commit this afternoon, VMware's José Fonseca made the change to begin advertising GLSL 3.30 as the GL Shading Language support level for Gallium3D's LLVMpipe. This change comes with all necessary TGSI support being there "in theory."
The change allowing the greater GL Shading Language level can be found via this Git commit. Aside from the shading language support, there's also patches for OpenGL 3.3 support in LLVMpipe.