Google is scheduled to announce today a beta feature for AdWords that will allow advertisers to specifically target selected content sites in the Google network, reports SearchEngineLowdown. Google will test a cost-per-impression bidding model for AdWords ads (not on Google's search results page - only its network of partners), and for the first time advertisers will select which websites on which their ads are displayed.

The New York Times writes that Google's advertising network will likely become more important to its business than search, and quotes an author of an upcoming book on Google: "It is an advertising business that has nothing particularly to do with search." The Times says the move comes as Yahoo is preparing a significant expansion of its service to place ads on other websites and has been experimenting with graphical ads. Yahoo has long offered branded advertising, but mostly on its own site.

CNET writes that last week Yahoo was touting its flexibility in selling search or display promotions in the future, having just reported more than $1 billion in sales of advertising, including brand ads. It adds that Google's new program, called Site Targeting, will allow advertisers to target ads not only by website but also by category. Google will target ads by scanning webpage content.