I've been remiss in not pointing this out sooner. David Weinberger, who has quite a bit to say about the nature of the Web and digital media, delivered this lecture to the Library of Congress a year ago November. If you're at all interested in why digital media is different from what came before, watch this lecture.
Here's a hint: it's all miscellaneous.
Weinberger's web log, the Journal of the Hyperlinked Organization also has a page with links to the follow-up Q&A. The presentation was part of the Library of Congress' Digital Future series.
Weinberger is the author of Small Pieces Loosely Joined and co-author of Cluetrain Manifesto, both seminal works on the nature of the Web. He has also worked with Woody Allen as a joke writer.