http://www.reuters.com/article/idUSTRE62E5FD20100315?type=technologyNews

From Reuters:

"Google Inc said that it expects the rates that companies pay for search ads on mobile phones could surpass the rates of its existing PC-based ad business thanks to the growing popularity of powerful smartphones.

Google Engineering Vice President Vic Gundotra did not say when he expected the crossover in the so-called cost per click of its search ads to occur, during a webcast to analysts about the company's mobile business on Monday. But he said that mobile ad rates have increased "dramatically" in recent years.
...."