One member said that his rankings "jumped from 168 to 29."
But is this update causing technical problems with searching over at Yahoo? An other WebmasterWorld thread reports Yahoo is telling searches they can't process their query:
We had temporary problems searching for web pages. Search again for MY SEARCH or type a new query above.
Aaron Wall at SEO Book seems to be the first to spot and call out this Yahoo update. He said he has seen a shift in rankings and problems with how they handle 301s, and a change in how they weight on domain names. Loren Baker also covered Aaron's post.
Update: It is now official, the Yahoo Search blog just posted a weather report.