Dave Winer -- Opines about where RDF is at.
Before there was a World Wide Web, there were big technology companies with ambitious plans for networking and application integration, and interop between competing software. Apple had OpenDoc and Taligent in partnership with IBM and a bunch of other companies. Microsoft had Cairo and various mail and database APIs, some in partnership with other companies. It seemed every company had their own roadmap, the industry made mundane mature products, PCs and Macs; and mostly incomprehensible white papers and bookshelves of incomprehensible documentation, and not much inbetween.
Then along came the Web and blew that all up. You didn't even need to read the docs to figure it out. Just View Source. That was good because there were no docs.
So I am a disbeliever of anything that requires as much documentation, head-scratching, hand-waving, and eyes-glazing-over as RDF does in 2002. Forget the problems with the formats, that can be dealt with later, after you figure out how to explain it to someone who knows a lot about computers, networks, users, XML, HTTP, etc. If you can't explain it to me so that I understand what you're doing -- you've got a big problem.
It's a cute, and all-too-common tactic to say that people who don't get it are dumb. I'm not dumb, but RDF makes me feel that way. After all these years, I've concluded that if I can't understand it, it doesn't have much of a chance in the market. All the powerfully successful technologies of the past have had simple explanations anyone could understand. If RDF is one of those, I strongly believe it must too. Therefore I conclude that it isn't.