In what has to go down as the greatest April Fool's joke in SEO history, Matt Cutts and Jeremy Zawodny, convinced many SEO buffs that they had indeed switched places a little over a week ago.
The truth is that Cutts is still and employee of Google and Zawodny is still an employee of Yahoo. Cutts confirmed as much on his blog this past week.
No one can say that Google and Yahoo don't have a sense of humor anymore.