I found this fascinating quote today:

The simple fact is that all the search engines are looking to improve revenue and they are no longer going to be satisfied with merely selling ads for the searches. Now they want to sell ads for the results pages you click on, too. And that strategy favors large information providers, not small businesses. Where search was once one of the few forms of marketing where small businesses had a level playing field against large ones, I think that each day the field is tilting a bit more.Search Engine Guide Blog, Jun 2009

You should read the whole article.