Is there an open source renderer us new guys can use with OSL?
Sort of, it's integrated into Blender but they don't expose the ability to add new shaders o_0.
As of a few days ago, we now have a mini renderer called testrender that ships with the OSL distribution. But its only intended for very simple tests (it only supports spheres and quads).
If you are looking for something more feature complete, I recommend waiting for support in Appleseed. http://appleseedhq.net/
unicomp: Yes this is for real, you can download it from blender.org.
I think this issue can be closed.