Read/WriteWeb has a very well considered article on "Competing with Google Search".

The article begins:

Search is still a crucial paradigm and so all the Internet bigcos continue fighting for position - and some of them ultimately aim to usurp the search leader, Google. In this article, we take a closer look at the competitive advantages of Google Search and try to find out whether Google is really beatable.

The article then goes on to provide us with eight competitive advantages Google has over other search engines.

In summary we are told that the obstacles to competing with Google are huge but not totally unbeatable. The closest we see a competitor to having enough clout is Microsoft. However, there would have to be a huge effort on the part of Microsoft for the new world order rather than spending so much on maintaining the old software way of earning a living.

In conclusion the writer states that Google can be beat, but that anyone who wishes to beat Google had better have very deep pockets and be committed wholly to a new paradigm that might Usher Google out the door.