If You work with CAD Modeling Programs like Rhino, Alias, SolidWorks, MOI or any other program, you know how ugly the imported Files looks in Blender internal renderer. It's because Blender internal renderer doesn't support (no it just ignores) imported vertex normals. For example lwo-files support vertex-normals. There is one script that can import meshes with vertex-normals into Blender, but it means nothing without possibility to render it.
Here is a small example:

with and without vertex-normals import:
http://home.comcast.net/~gamma-ray/moi/normals.gif

You can read more here:
http://moi3d.com/forum/messages.php?webtag=MOI&msg=979.1

So PLEASE implement this feature, its already become a standard in all render engines (except of Blender)