Their new search engine personalizes Yahoo search results using your Friendster social network. From Chris' article:
- Search results are prioritized with results viewed by anyone in your personal network appearing at the top of the list. These results are highlighted with a smiley face icon.
On the other hand, I'm not sure how often this will change the search results, whether the changes will focus your attention on the most relevant result for your search, and whether it is scalable to access search and clickstream history for everyone in your social network on every web search you do.
Nevertheless, it's an interesting development, an unusual use of a large social network to do a version of personalized web search.