Small update...
Hi there.
Revision 71 is here and it has the following key features implemented:
The scene editor is now highlighting C# sourcecode. That makes sense beacause I implemented the necessary routines to assemble scene objects from C# sources using the CodeProvider and Compiler Objects. (Actually "using" Microsoft.CSharp; System.CodeDom; System.CodeDom.Compiler; and System.Reflection; :D )

The next step will be to create open and save routines for the scene's code and settings. Best would be to have both in one file. And maybe to compress this file, because as soon as I will have vertices for polygons and the like to store, the file size will surely explode. This leads me to another idea: Having polygonal data in "resource file" like structures - so the scene code remains clean and the models (maybe in a standard format like obj) remain viewable (and maybe editable) by third-party programs. But there's still a long way to go until efiRay will render 3d models.
Well. Now, the fact that efiRay can build scene objects from code may be nice but is not that impressive, I guess. The other good news are: The renderer is back! ("Back" in terms of "entirely written from scratch")
Take a look at it here - It features a rendering pipeline, image transparency and live preview updates:

The screenshot shows the rendering-in-progress of the above listed sourcecode. I am currently working on the first raytracing module that will be used as preview renderer for materials. The next modules for the pipeline will be ambient occlusion and depth renderers, since they are not too hard to implement, I hope.
But befor that I need new primitives. Spheres only are not really satisfying.
So stay tuned!