Actually, no one at Google has modded the search engine to show the autobiography of Dubya when one searches "failure." Rather, this result was done by using a method called googlebombing.
In a nutshell, googlebombing works by having a whole bunch of people click on a hyperlink that says "failure" that leads to our favorite president's autobiography. When Google's web crawlers look at the immense traffic from one site that links "failure" to the web page, Google automatically assumes that the word "failure" links to "George W. Bush," and thus, the top result for "failure" is the autobiography of Bush Junior.
As is seen by the later results, Republicans tried to top this by linking "failure" to such Democratic people as Micheal Moore and Jimmy Carter, however the sheer volume of people clicking on that little link is still holding.
