the PresentationAgent is the "clever" part of the IntelligentBrowser, which guides one over that SeaOfContent (you know -- the one chock-full o' MoreSophisticatedReferencing).
The PresentationAgent will monitor the user's actions. Ideally, it would somehow understand those things the user found most interesting, least interesting, or of passing interest.
The agent would then decide for itself what information to present -- if someone quoted a book/paper that you've read, the agent could present simply the title. If you've not read it in a while, or if you probably won't care about it, it could present a turbo-quick synopsis, and a ref to an abstract. If it thinks you want/need to learn more before continuing, it could present a full abstract and reference the whole work. (someone please flesh this out for me)
It would be nice if we could also "spike" interest in a topic area, thus giving our PresentationAgent a mission, searching for relevance in the SeaOfContent, effectively acting as a search engine, finding and presenting those things of current interest.
Ah, the fallacy of the ExplicitUserModel, beautifully skewered in BrendaLaurel's ComputersAsTheatre.