Today I wrote a quick "preview material" feature.
It was made as a test to see how easy it was without rewriting the whole exporter.
This is what it does:
Writes out a lxs file that has the geometry etc in scripts folder.
writes out a lxm that contains the material
includes the lxm in the lxs file.
spawns luxconsole, renders image, then opens image in preview box.
It preview the current selected material in material editor..
This might be a bit different from other suggestions (preview in the material itself..).
At least this is how it is right now.
It needs a bit more work before I release (just some basic stuff that needs to be in place).
also all preview settings is hardcoded right now.. this will be exposed in the material preview rollout.
here's some samples:
