http://www4.wiwiss.fu-berlin.de/bizer/SWTSGuide/

You frame the issue of trust nicely though. Very practical description.

And I agree with the previous commenters; ‘better search’ isn’t my grand vision of the Semantic Web either. Intelligent agents, improved data quality, and easier ways to exchange data are the things I’m really looking forward to.

But your point is a very good one – as we get more machine-readable data on the Web, questions of trust and provenance become considerably more significant. So far we’ve only really seen “lower case” semantic web approaches in the wild, e.g. I’m likely to trust the tags you use in your del.icio.us feed because I trust you. (Note also that these pieces of metadata are out-of-line, not actually in the documents being referenced).

If you can make rich descriptions of resources (as Semantic Web technologies allow), then one at least has a way of saying “I believe this” or “this is a lie”. Generally the statements in question are associated with URIs, and with the Resource Description languages there is a means to express levels of confidence in those resources (thus the “upper case” Semantic Web approach).

There’s a paper around called “Named Graphs, Provenance and Trust” (Google!) which talks of RDF graphs, but if you bear in mind that a HTML doc (at a given URI) can be considered a named graph (named with the URI, the graph being all the machine-readable statements it contains) then there’s a relatively straightforward mechanism for dealing with this stuff.

While I don’t imagine it occurring outside of specialist applications any time soon (again as Ryan suggests) inference can also help. An advanced example of this is Tim Berners-Lee’s “Oh Yeah?” button, which you press to discover the chain of authority behind any statements you encounter.

http://www.w3.org/DesignIssues/UI.html#OhYeah

But, to answer your question, describing data semantically is only half of the equation. If it stopped there, then it really would be no different than other existing meta information out there (meta, tags, categories, even keywords). The other half is being able to write algorithms that can emulate the human abilities of inference and deductive reasoning. A semantic search engine should be able to deduce that a page is not what it purports to be because the data it describes does not correlate well to similarly described data from other sites.