If you’ve ever heard or seen the phrase “Trustrank” before, it’s possible that whoever was writing about it, or referring to it was discussing a Yahoo/Stanford paper titled Combating Web Spam with TrustRank (pdf). While that TrustRank paper was the joint work of researchers from Stanford University and Yahoo, many writers have referred to it as Google TrustRank since its publication date in 2004.
While Yahoo has a TrustRank approach, Google does not have a similar approach. The Yahoo approach is aimed at identifying Spam on the Web. It has been patented, under the name Link Based Spam Detection. Because that Yahoo patent exists, Google could not be granted a patent that covers the same processes – the USPTO would not grant such a patent. However, there is a Google TrustRank.
The confusion over who came up with the idea of TrustRank wasn’t helped by Google trademarking the term “Trustrank” in 2005. That trademark was abandoned by Google on February 29, 2008, according to the records at the USPTO Tess database: