The more I think about the Semantic Web, the more it sounds like very earnest barking up the wrong tree. I have always been leery of Metadata and especially that defined by the writer of the material in question. The whole point of Metadata is to in some way create a container for the content so that it can easily be identified by others. This is the supermarket model for the web; by putting all the tins of beans together we can make selection more efficient, drive up the total sales and we know this because the labels and the tins all tell us that these are beans.
I have every sympathy for the supermarket owners, they need this classification system and so do we, but that isn't the net and never will be, it is a commercialised view of the world that, above all, tries to brand information. It allows me to label things that will help MY information stand out from other people's. Now naturally the semantic web people want to mandate truth in advertising and all those play-nice things, but it will take about 10 minutes for someone to start gaming the system and it will go to hell in a hand basket. While it is possible to game Google, it is much harder and requires an overt conspiracy among many participants. At which point the gaming itself becomes a game, but not a tool to gain unfair advantage.
The whole point, as far as I can see, is that semantics try to make endemic to the document something that is inherently extrinsic (semantics is a description of a language, it is NOT an instruction kit) words are internal to the document but the meaning is contextual and mostly external.
On the other hand, a hologram is a much better model. You can focus till you go blind on the data in the hologram and you will be no wiser, to extract it meaning you have to shine a light through it and look away from it, what's more, it scales.