Yahoo announced a new search update, or what they call a "weather report" for their index. Yahoo said you may notice ranking changes in the Yahoo Search results. They said:
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.
I have not seen any discussion around this but there may be an issue with the Yahoo Search WebmasterWorld forum, so I am not sure.
Update: I was able to post a thread at WebmasterWorld (maybe there was a bug on my side) and now we have a nice amount of feedback on how significant this update is. Here are some posts from the thread:
I'm seeing a small but statistically insignificant increase from Yahoo!
We had been showing a steady increase in traffic until yesterday (March 10th). Today, we've lost about 20% of our traffic from Y!.
This is a pattern that seems to repeat with each update. After the update we drop in ranking but slowly climb back before the next update.
They are showing lots of love for Wikipedia.
I'm seeing huge differences not in the results but the output...5 natural results for some queries instead of the usual 10 and quite frankly I like it shortened like this. Top 5 or go home.......