Last Thursday, July 19th, the Yahoo! Search Blog announced that they have started rolling out an update.
We've been rolling out some changes to our fresh web data and crawling, indexing and ranking algorithms over the last few days. We expect the update will be completed by the weekend. So, as you know, throughout this process you may see some changes in ranking as well as some shuffling of the pages in the index.
Since then, I have been waiting and seeking out threads discussing changes people have seen to the rankings in Yahoo. But I have yet to see any thread discussing any shifts and changes in the Yahoo Search results.
Typically, the forums spot these updates before they are announced. In this case, the announcement was made and still, there is fairly no discussion about changes in the search results.
There is a WebmasterWorld thread discussing the announcement of the update. There is one person saying he saw an increase in traffic from Yahoo, "One of my site was getting 1 or 2 daily from yahoo, suddenly it got 10 so far now." But outside of that, the only discussion in the forums I track are from the Y!Search Blog announcement.
Forum discussion at WebmasterWorld
Update: People are now discussing minor changes in ranking.