According to an interesting article on the American Marketing Association website:
"Search ad spending is now responsible for 40 percent of online ad revenue, and by 2010 it should surpass display advertising, according to JupiterResearch. In fact, Jupiter finds some erosion in support for the traditional banner ad but persistent interest in search. In another recent analysis of the top information companies, Outsell sees clear signs that increased search ad budgets are starting to make a dent in overall publishing industry income. "Seven of the ten giants own significant newspaper and magazine assets, and Google and Yahoo! are clearly diverting advertising revenue from them," they report."
Image: screen grab from Google.com