Search engine Yahoo will allow third parties to add extra details, such as ratings and reviews, to their search results. Its new open source application called "Search Monkey" will allow publishers to add information such as rating and reviews, images, deep links, etc. to Yahoo SERPs.
To me it's like the meta-data 2.0 (aka old age meta tags go web 2.0)
So the new set of meta-data for let's say a website of a online store may include ratings, price information and links for reviews and photos with the new tools. Yahoo plans to provide additional details on how the open search tool will work over the next few months.