Those materials need a custom GLSL shader since the basic default one does not support reflections.
A small tutorial on this topic: http://antongerdelan.net/opengl/cubemaps.html
This will also be helpful for water surfaces etc.
Maybe we can create a shader pack for distribution in our “Asset Store” (btw: We need a name for it :p)
I wrote a very simple per-vertex shader that does this using a sphere map.
Maybe I will create a “NeoShaders” git repository on GitHub to distribute all sorts of GLSL experiments I’m doing.