Besides easing our everyday e-life, the Semantic Web will, most probably, also end the present day Babel Tower of Health IT intercommunication protocols (HL7, X.12, HXP and others).
Some of the concepts in the following article are not easy to follow, but they surely deserve some of your time. I wonder, why was the article's example taken from healthcare?
"The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation." -- Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001 .
Further reading and technical papers may be found at: The Semantic Web home at W3C