Specifically Google bombs are created by linking to some unused phrase that brings up irrelevant results when searching for the bombed phrase. The articles linked go into this in more depth.
It's been quite some time that the George Bush bomb has been on Google. At least a few years. If they claim they are against this kind of bombing, then WHY didn't they remove it? Basically their reason was this:
"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."
Ah, so it doesn't matter if their search engine insults the president. As long as it's a good engine, one or 2 insults don't matter... They also state here:
"The next natural question to ask is 'Why doesn't Google just edit these search results by hand?' To answer that, you need to know a little bit about how Google works. When we're faced with a bad search result or a relevance problem,"
So THAT explains it. Google thinks that if George Bush doesn't show up under the search term "failure", then it's irrelevant. It's great to see how apolitical Google is these days. When they finally get around to fixing it, all they really do is change their search algorithm that "helps detect Googlebombs in many different languages". Well, let me tell you something: a human is A LOT smarter than a computer, and no matter how efficient and fast it is, this is certainly not the end of Googlebombs.
So sit back and let Google show us their brand new anti-bombinb techniques (and likely some other insulting phrase). What a pity.