I had been desperately looking for some software emulation for ARB Vertex/Fragment programs in OpenGL for a past few days.
I have a pretty shitty display chip on my notebook, ATI 345 IGP. Well, not all that shitty though, it does support vs 1.1 in hardware. However, the OpenGL driver that I presently have doesn't export a vertex program extension (is it expected to?).
So, in search for vertex/fragment programs software emulation, I found MESA. I had previously ignored MESA as software emulation stuff for OpenGL(who needs it anyways, I have real hardware!), but now it bounced back again into my head. The current version 6.2.1 supports ARB_vertex_program and ARB_fragment_program. I ran a test application with it yesterday and it seemed to be running great (I just ran a vertex program, not sure about fragment programs yet). I'll be looking forward to MESA coming out with ARB_vertex_program_100. I would then be able to try out some GLSL with it, but well, Cg is working fine for me at the moment and I hope to have a better machine sometime soon.