Laurence, do you understand how Google makes money? It practically prints its own dollar bills. It is all-pervasive. It is all-controlling. That's why it's so valuable.
Here's a glimpse into the inner workings. Almost every consumer who logins to the internet to shop or find out something does a google search. Google returns "hits" in the order that folks pay them to place them. So my company uses Google. We pay google 5 cents or 3 cents or whatever so that when someone searches for "widgets" or related keywords, then our company appears in the list near the top. Everytime someone clicks through to our website, google bills us. We buy a whole collection of related keywords. Google knows which keywords that consumer use the most and charges more for those keywords.
In essence, google collects taxes on all internet commerce and searching. It's a very small tax, but it's there. In fact, many companies are afraid of google. After all, it controls a big fraction of what people will see on the internet. Folks search, google presents. If google decides to blacklist a company and never put up that company's website in a search, that company is screwed.
Suppose google builds a local yellow pages online phone book. Imagine how useful that would be. Imagine how much local companies would pay to be placed near the top of the search list. Imagine that the companies only had to pay a dime for each click through. They would think it was cheap. Google would clean up.
Full disclosure: I do not own Google, nor do I own Yahoo.