unitone said:

Google's PageRank patent is dead. No more software patents. A new position taken by the Patent and Trademark Office, in a series of cases, will invalidate most software patents. Inventions are patentable only when they "result in a physical transformation of an article" or are "tied to a particular machine". A general purpose computer is not a particular machine, thus software can't be patented. Google's PageRank, the most famous software patent in history, will be rendered invalid by the PTO's new rule for patentable subject matter. http://www.patentlyo.com/patent/2008/07/the-death-of-go.html