Facebook Ranks as Top Display Ad Publisher in Q1 2011
Popular social networking site Facebook.com led all online publishers in Q1 2011 with 346 billion display ad impressions, representing 31.2 percent market share. Facebook’s market share has increased 15 percentage points from 16.2 percent in Q1 2010. Yahoo! Sites ranked second during the most recent quarter with 112 billion impressions (10.1 percent), followed by Microsoft Sites with 54 billion impressions (4.8 percent) and AOL, Inc. with 33 billion impressions (3.0 percent).
U.S. Online Display Advertising Market Delivers 1.1 Trillion Impressions in Q1 2011 - comScore, Inc

Check the Total U.S. – Home/Work/University Locations in the article.

It seems like the search ads business is going somewhere else...