Yahoo Search sent me a note that tomorrow they will be rolling out a new update. Yahoo told me that they made “some changes to their crawling, indexing and ranking algorithms.”
The update is expected to be a quick one, but you may notice “ranking changes and page shuffling in the index,” according to Yahoo. I personally did not see any changes as of yet, nor did I see any reports of changes in the forums. Yahoo has a post at the Yahoo Search Blog.