Peterme is talking about content genres right now. In a nutshell - in print, genres are things like textbook, guidebook, or map. On the web, genres include things like academic papers, FAQs, Testimonials, etc (yes, there's a lot of overlap). Genres help set expectations about how to use the content, and what kind of information you will find there.

One of the implications of genre is that content can't be easily repurposed across channels - a genre like a "real estate tour" just won't work in print, over the phone, or on a mobile phone if users are expecting a rich media panoramic experience. Instead of convergence, we get "meaningful divergence, with the right content to the right device".

I think that there's a lot of useful applications for the ideas...and there's similar work happening with Microsoft's application archetypes At the same time, I'm skeptical that the web is mature enough to really develop a robust collection of genres or archetypes. However, genres don't have to be complete, or fixed - like design patterns, use what's useful, and don't try to boil the ocean in creating an exhaustive list of genres.

Links from Peter
Collection of Papers
Andrew Dillon's Publications
Book: Tracing Genres Through Organizations