I doubt the interpretation being proposed here. Contract/license law errs on the side of the licensee. If there is an ambiguity, the licensee cannot be found in breech. Every single license agreement that I have seen that tried to be "free for personal use" but "charge for commercial use/redistribution" made this EXPLICIT in the licensee agreement.
Thus we have two scenarios, either:
#1 NVidia really did mean to require commercial entity who uses Cg source code to obtain a separate license and their lawyers are grossly incompetent and thought a single word without a definition section in the agreement would protect them
or
#2 As NVidia has stated, Cg is "open source" and Nvidia hopes other commercial entities will integrate Cg into their products.
If NVidia really did intend to restrict Cg usage by other commercial entities, that would imply their lawyers did a crap job with the license AND they would be directly contradicting their own public statements about the direction they plan to take Cg.
It just doesn't add up.