Still living in the 331.xx series, this NVIDIA driver update isn't as exciting as some of the major NVIDIA Linux releases of 2013, but overall it's still a great release.
The NVIDIA 331.38 Linux graphics driver this morning fixes an X.Org Server crash when out of dedicated vRAM and not able to render to system RAM, updates to the NVIDIA driver installer, updated NVIDIA Settings, an NV CONTROL attribute for controlling the brightness of illuminated logos on certain graphics cards, a screen transformation bug-fix, and GLX protocol updates.
The GLX protocol changes include acknowledging the promotion of several extensions to being officially approved by the ARB: GL_ARB_pixel_buffer_object, GL_NV_conditional_render, GL_ARB_map_buffer_range, GL_EXT_texture_integer, and GL_ARB_vertex_array_object. The GL_ARB_pixel_buffer_object extension was the last bit of the protocol needed for official support of indirect rendering with all OpenGL 2.1 commands.
Other bits of the GLX protocol for OpenGL 3.0 commands were also moved to being officially approved by the ARB. Various bits of the NV-CONTROL extension were also deprecated in this driver release.
More details on the NVIDIA 331.38 Linux graphics driver changes can be found from the NVIDIA.com web-page.