I've been trying to get my head around the SemWeb space - specifically, RDF and it's many abbreviated friends (OWL, GRDDL, SPARQL etc.). 
Like microformats, it's very easy to over-estimate the complexity of these things. I've jumped in, and I'm turning out RDF files and have successfully queried one using SPARQL. Next up, I'm going to try and write a schema - hopefully Shelley Powers will help me along (at least her incarnation in Practical RDF).
So, below, I'm providing a Semantic Web reading list. These are links I've found in my search that describe the idea of the Semantic Web and describe it's implementation.
Tim Berners-Lee, Business Model for the Semantic Web.
Tim Berners-Lee, Semantic Web Roadmap.
Dan Brickley, Understanding RDF.
there was a realisation that the world isn't parcelled into distinct metadata communities and that any solution would need to mix and match overlapping data structures defined in multiple application domains
Edd Dumbill, The Semantic Web: A Primer.
Technical peeves aside, the value of the Semantic Web is to solve real problems in communication. First and foremost this means radically improving our ability to find, sort, and classify information: an activity that takes up a large part of our time.
Berners-Lee, James Hendler and Ora Lassila, The Semantic Web (New Scientist).
The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation... For the semantic web to function, computers must have access to structured collections of information and sets of inference rules that they can use to conduct automated reasoning.
Want to see something really cool? Take a look at Semantic MediaWiki, an extension for MediaWiki that allows you to define semantic data inside wiki articles and have that exportable in RDF format.
