Well, they have also tried to make revenue in other ways but haven't done well with Google checkout and Google Apps for Enterprise, if they are so happy with ad

Well, they have also tried to make revenue in other ways but haven't done well with Google checkout and Google Apps for Enterprise, if they are so happy with ads they wouldn't be doing Google Apps which is basically not their main forte (enterprise customers, actual support, non-free web apps) Dependence on ads for money is like the Google's Achilles heel right now.