Just heard of this tool from Thomson Reuters, which works on Drupal for one thing which is interesting:
Calais: Connect. Everything.
We want to make all the world’s content more accessible, interoperable and valuable. Some call it Web 2.0, Web 3.0, the Semantic Web or the Giant Global Graph – we call our piece of it Calais.
Calais is a rapidly growing toolkit of capabilities that allow you to readily incorporate state-of-the-art semantic functionality within your blog, content management system, website or application.