My notes are here. I'll update this with more content soon.
Updated: I've improved my notes.
Also, you can find more detail on obscurance here, in a paper from Zhukov et al. in 98, and an improved version especially for games here, which they published in 03.
The paper we looked at on approximating incoming light with outgoing light, by Stewart et al., is here. Hoffman and Mitchell's implementation for gaming terrain is here, with their code here.