Yahoo is testing a new search engine that gives uses the ability to sort results according to their preferences users can switch from commercial to informational search results.
Through the use of machine learning for text classification, we try to classify each web page in the top 100 search results for a query. Then we sort those results according to the preference you set. Mindset uses an intuitive slider in the interface, so you can set the bias for commercial vs. non-commercial results. Often, we come across a web page that hasn't been classified yet. In those cases, Mindset tries to classify that web page in the background, so it'll be classified along with the rest of the results next time you do the same query.
The Mindset search engine is described as a technology demo as Yahoo firsts wants to test whether Mindset is effective and if users like it. Yahoo Mindset can be tested here.