Posted on Friday evening was a patch to enable OpenGL 3.3 and OpenGL Shading Language (GLSL) 3.30 for Intel "Gen6" Sandy Bridge hardware with Mesa. It's believed all other functionality needed for GL 3.3 has already been reached for the Sandy Bridge code-paths.
Independent contributor Mike Lothian wrote, "I'm pretty sure this is all thats needed to switch on GLSL 3.30 and OpenGL 3.3 on Sandybridge."
Of course, thanks to Piglit it should be very easy to determine whether or not all of the necessary functionality is in place for Intel Sandy Bridge to properly advertise GL 3.3 on Linux. Intel's Mesa driver for Ivy Bridge and newer already advertises OpenGL 3.3 while the Intel Open-Source Technology Center team is still hard at work in reaching OpenGL 4 compliance.
Update: Chris Forbes of Intel went ahead and committed the support.