Here this refers to search engines which have a database of entities (people, places, things).
They scan news articles for what entities they contain and how they relate to each other.
This allows one to find articles that are about a particular entity, even if they don’t include certain keywords, and also jump from articles about one entity to articles about related entities.
October 20, 2010: Major overhaul of the page. Removed most search tools and links and added many new ones. New sections include blog search engines (the same as included on the search engines page). There's also an informational part which explains the semantic search engines section.
December 5, 2003: Logging updates from now on. This page was created previously.