Not that that would be a surprise. But even with things that should be standard Maya finds ways to fuck things up. If you export an object as FBX from Maya, it exports the material with it. If you export the same object as an OBJ-file, the .MTL-file (which has the material definitions) uses the shading group names as references! And of course, those have no direct relevance to the material name... Why, Maya, why?