Drop3D is a plug-in for Illustrator CS3 - CS5 that reads 3DM, IGS and oddly enough VRML 2 files, and converts to vector and/or raster format.
It's does a good job with curves, (not quite as good as Michael's AI export) but supports hidden line removal or hidden line as dashed line for
custom line isolation.

I did a quick video to demo workflow in action:

http://vimeo.com/34016658

Here's some screen caps of results: