"We've been testing different advertising formats for years (some have been more successful than others), and over the next few months, you'll see us continuing to experiment with new ads in new places. (...) Whenever we make changes like these, we carefully evaluate users' reactions to ensure we're holding true to our basic principles: that ads by Google should always be relevant and useful. Of course, these experiments benefit Google because they generate revenue from new sources — but by ensuring that we show the right ads at the right time to the right people, we'll add value for users too," explained Google in November.
Now that the revenues from advertising grow much slower than in the past, Google will probably launch more paid services like the App Engine or Google Apps Premier Edition. Even Google Checkout, a service that has been subsidized by Google for years, will use the same processing fees as PayPal from May.