Since the “Mask” feature in the material’s transparency settings (good idea, btw.) was introduced, appearently the material nodes don’t support transparency anymore? I guess I’m missing something, but neither preview nor render show any z- or ray transparency.
When I load a file created with 2.55 into 2.57, the transparency works in the editor, also the “mask” setting in the imported material does not show up, so I guess, there is a link betwenn them.
Also Volume materials don’t work there, but I guess that’s not intended anyways, right?