The J.R.R. Tolkien of the Web
rhwalker22 writes "In a column titled "Lord of the Webs," The Washington Post's Leslie Walker looks at Tim Berners-Lee ("the J.R.R. Tolkien of the computer world") and the Semantic Web project. Berners-Lee was in Washington recently to tout the project: 'In his futuristic scenario, the Semantic Web offers controlled access to American health care data, plus databases charting the location and status of rivers, underground water, forests and local vegetation, along with economic data on local industries and what they produce -- all marked up in special vocabularies. Those allow scientists to run global queries across the Web, fishing randomly for correlations that might exist between where the sick people lived, worked and played -- such as a polluted stream or industrial dump.'" See an older article on the Semantic Web.
Have a look at this article by James Hendler which talks about the use of the semantic web in an agent context. Trust is right at there at the top of the layering cake that make up the semantic web.
As for usefulness, time only can tell of course, but there is certainly a lot of research and development being invested in making this happen.