I have been received emails and notes asking me if there are any reports on a Yahoo! update. Well, there is one thread that I noticed at WebmasterWorld that has people discussing a bouncing pattern going on at Yahoo! Search. The deal is that not too many other forums are discussing this behavior, so it is hard to isolate if this is happening at a large scale or within a small niche of themes.
So you decide.
Forum discussion at WebmasterWorld.