Adsense relatively makes little since they pay most to site-owners, whatever they call the ads on Google make the money. After 11 years has, Google has what, other than search?
YouTube. Android (their market share isn't declining). Likely the most popular cloud office suite. GMail. Picasa. Google+. Analytics.
Just to name a few.
I'm pretty sure AdSense accounts for around 30-35% of Google's revenue.
Android would last a couple of hours without Google's tens of billions in protection. Isn't it free anyway?
Revenue vs earnings matter on Adsense. Their pay and inventory is linked to the power of Google.
So in the end Google has, search.
Can G out-Microsoft Microsoft in Office? I doubt it. Analytics and everything else is subsidized by search.
You can see their Q4 2010 earnings statement at http://investor.google.com/earnings/2010/Q4_google_earnings.... . Here is the relevant portion for AdSense:
"Google Network Revenues - Google's partner sites generated revenues, through AdSense programs, of $2.50 billion, or 30% of total revenues, in the fourth quarter of 2010. This represents a 22% increase from fourth quarter 2009 network revenues of $2.04 billion."
If publishers are paid 68%, this means Google's share is roughly $650mill for that quarter.