There are signals from the forums and via Twitter of a possible Yahoo update. Yes, Google seems to be updating as well, but so is Yahoo.
Vanessa Fox, former Googler and now Search Engine Land's Contributing Editor tweeted that on her sites, "Yahoo Slurp has super slowed down its crawl."
Are you seeing changes in your rankings or in the crawl speed of Yahoo Slurp on your site?
Forum discussion at WebmasterWorld.