One day after the easy projects were announced, there was already one project being worked towards completion (and it's since been completed) by a Phoronix reader. There's also another project still outstanding with new patches being published.
Pi Tabred is up to his second version of patches for implementing ARB_clear_buffer_object support within Mesa. The code adds close to 500 lines of new code to Mesa by this new contributor. The GL_ARB_clear_buffer_object extension provides a way to set OpenGL buffer objects to a known value, per the OpenGL.org registry spec.
The current set of patches for this extension enablement in Mesa can be found from the Mesa-dev mailing list. Those interested in diving into the world of Mesa 3D open-source driver development can find other projects to get started on via the FreeDesktop.org Wiki.