"If HTML and the Web made all the online documents look like one huge book, RDF, schema, and inference languages will make all the data in the world look like one huge database."
-- Tim Berners-Lee, Weaving the Web, 1999
"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
W3C Semantic Web
Wikipedia - Semantic Web
Also, if possible, grab a copy of Newsweek Special Edition. It includes essays by King Abdullah II, British PM Tony Blair, Singapore PM Lee Hsien Loong, Eric Schmidt of Google, an interview with Tim Berners-Lee and of course, Fareed Zakaria of Newsweek.
Technorati: Semantic Web, Semantic-Web