Resource Time: Structure and Semantics on the Web?
I cam across a great introduction to the structured web, I would encourage you all to have a read, the quality og the series so far has been excellent.
While on my travels I also came across a good introduction to the semantic web, while it is slightly outdated a lot of the stuff being talked about is still relevant today.
So enjoy those two links, I will also be placing them on the iDevs del.icio.us page for future reference.