I noticed the GLSL1.30 specification does not mention certain things that are mentioned in GL_ext_gpu_shader4 extension. I thought they should be identical.
In particular I checked the GLSL1.30Revision08 and with no word it mentions the texture buffer objects and its specific sampler: samplerBuffer, isamplerBuffer and usamplerBuffer.
Hmm yeah I went through all the specifications again and all the annoucenments and I saw that texture buffer objects are considered as an extension only. Which is a major bummer since that is quite a powerful feature (and fully exposed in other APIs)
Btw, they just posted a new glext/wglext.h today. Got all the new ARB procs/enums, including those for ARB_texture_buffer_object (and ARB_geometry_shader4 too 8-)).