Powerset is a discovery tool that (currently) extracts and organizes information contained  in Wikipedia and Freebase. A natural language algorithm allows the searcher to use keywords, phrases, or even simple questions.  The results page aggregates information from across multiple articles, in essence creating an enhanced Wikipedia article.For example, here is the search results for Thompson Library.Powerset (purchased by Microsoft in 2008) allows users to highlight passages which persist when the URL is bookmarked or shared the URL.  Once the URL is copied and shared, the modified page will automatically scroll to the highlighted section. It’s great for sharing notes on Twitter or posting a specific sentence in context into a blog.For example, let’s say that you wanted to share that information that it has been reported that the size of the Thompson Library is expected to decrease 20% when it re-opens after the current renovation. As opposed to just sending that bit of information, one can send a link that directs others to the highlighted text. Now the the fact can be read in context of the Wikipedia article.The service also creates ‘Factz’ which are representations of information extracted from sentences. They are represented in three parts: the subject, relation and objects. Factz will appear for general topic queries on the search results page. On a topic page, Factz extracted from a given page in the article outline.The following video provides a nice introduction to the service.-Eric Schnell  [youtube]http://www.youtube.com/watch?v=b00bfZ8UDqs[/youtube]