The nv30 driver provides OpenGL 1.5 on nv30 hardware (Rankine) and OpenGL 2.1 with EXT_framebuffer_object on nv40 hardware (Curie).
It is known the nvidia 304.134 driver also provides ARB_framebuffer_object on nv40 (Curie). This also enables ARB_framebuffer_object with nouveau on this hardware.
Here is an example on an NV4A C51 Curie Nvidia GeForce 6150 LE (onboard GPU, HyperTransport bus) from an Optiplex 740 running Unvanquished that supports OpenGL 2.1 with ARB_framebuffer_object but doesn't support EXT_framebuffer_object. Note: the low FPS is because the models have too much bones and simplified models have to be shipped for such old hardware, this does not mean something is wrong on driver side. Edit: no, the low framerate is caused by #7631.
Previously it was known to not run on nouveau: