I can only find a user's manual for Cg 1.4 from Sept 2005, and the Cg Tutorial from earlier than that. Cg is now on version 3 and I'm wondering about all the new profiles and tech that must be in it... Anyone got some links?
The reference manual is up to date in the nvidia site Cg 3.0 Reference Manual, which i believe is where you can get most of the information you want. It does contain very detailed data of everything you can do with Cg, I don't think there's something missing there, but it may be hard to read at first as it's just a reference for all the technical aspects of it, you will hardly find something like a tutorial in it, perhaps there is some very small examples to explain some concepts (I'm gonna read some now it looks interesting).
EDIT: The manual doesn't seem to be that tough as I expected, if you have some experience with Cg or something similar already. I downloaded everything from the Cg Toolkit Download page. There it also mentions the users manuals and the demo tutorials were not updated, I believe you may find more updated tutorials on the web.
and this is The Cg Tutorial book, it may be useful for people interested in Cg