Google’s company blog has a post explaining Googlebombing:
If you do a Google search on the word [failure] or the phrase [miserable failure], the top result is currently the White House’s official biographical page for President Bush. We’ve received some complaints recently from users who assume that this reflects a political bias on our part. I’d like to explain how these results come up in order to allay these concerns.
Google’s search results are generated by computer programs that rank web pages in large part by examining the number and relative popularity of the sites that link to them. By using a practice called googlebombing, however, determined pranksters can occasionally produce odd results. In this case, a number of webmasters use the phrases [failure] and [miserable failure] to describe and link to President Bush’s website, thus pushing it to the top of searches for those phrases. We don’t condone the practice of googlebombing, or any other action that seeks to affect the integrity of our search results, but we’re also reluctant to alter our results by hand in order to prevent such items from showing up. Pranks like this may be distracting to some, but they don’t affect the overall quality of our search service, whose objectivity, as always, remains the core of our mission.