Yahoo! Announced search updates to its ranking algorithms on 10th March, 2010. This update includes crawling, indexing, and ranking algorithms.
Dan Rampton, Program Manager of Yahoo! Search writes on Yahoo Search blog:
The Yahoo! Search engineering teams are rolling out updates to crawling, indexing, and ranking algorithms. Similar to previous updates, you may notice some ranking changes and page shuffling during the process, which we expect to complete over the next few days.
Is this update is all about there Search alliance with Microsoft? Yahoo announced that they received clearance from both the U.S. Department of Justice and the European Commission for a search agreement with Microsoft on 18th February, 2010. On that occasion Shashi Seth, Senior Vice President of Yahoo! Search Products said:
Most of the things you see on the typical Yahoo! Search results page below will not immediately change as a result of this alliance. What will change is that the basic search listings and ads will be provided by Microsoft instead of our own back-end platform
Therefore, I think this update may be the implementation of these search results. I did not find much discussion about this on the internet, however we might see some significant changes on there search result shortly.
Related posts:


[...] Yahoo! Announced last search update to its search index and ranking algorithms on 10th March, 2010. [...]