Peter Norvig Web Search as a Force for Good

Is it remaining just a search engine for text on the web? Why is it venturing into the banner ad space, where there are plenty of well entrenched companies? How does Peter Norvig's solid background in Artificial Intelligence influence Google's search algorithms and its new services? How is Google managing to crack, in a seemingly easy way, the tough problems in linguistics and semantic understanding that researchers around the world are struggling to solve? How will Google defend its key resource, the vast amounts of data it collects on a daily basis, when the accessibility to such vast storage is becoming easier? What made Yahoo's once vaunted search bite the dust?