In the most recent issue of the Jimworld Gazette John Cokos states that he believes the recent Google algorithm shift may be due to the need to reinvent the algorithm wheel.

The PageRank patent is owned by Stanford. With that tie it may be hard for Google to go public without having to donate a large portion of future profits to the college. Some think Google is inventing an algorithm which replaces PageRank...With the recent changes this is rather plausible story, but only time will tell.