Its all about business, there is no permanent enemy or friend in business. Everyone has to work for fulfilling their own business goals.
Here is a live example to prove the above statement. You all know that Yahoo and Google are the main competitor in the Online World, apart from MSN. When I was googling for some information, I found a very peculiar AdSense ad which was for Yahoo VOIP service, voice.yahoo.com.
The image above depicts them all. Now the online business success is in Win-Win strategy.
Successful ways of blog and website promotion
Aggregate Yahoo! and Google search power through Firefox
Google knows themself better than other image search engines