This has already been possible for a while (though I think it's broken with current master?).
They ran the last time I tried them on HD4550. No anti-aliasing (and obviously no tesselation), but the rest seemed to work fine.
Unigine benchmarks do not need every single last piece of OpenGL3, and most of GL3 functionality has been in Mesa for a long time. They're just racing to finish up every last bit of it so they can advertise GL3 support.