On his Facebook page, Mark Zuckerberg explains that his social networking site is fashioning a more open world where people can "share what's important to them." Increasingly, the world's advertisers are also leveraging the platform to share what's important to them--to the tune of 346 billion display ad impressions in the first quarter of 2011.

ComScore is reporting today that Facebook doubled the number of ads it delivered during the same period last year and crushed all other online publishers, serving a whopping one in three online ads in the U.S. Yahoo, Microsoft, AOL, and Google rounded out the top five (AOL's display advertising, in fact, has been a bright spot in the company's otherwise dismal financial performance). The ranks of the top online advertisers were dominated by finance and telecom: AT&T finished first, followed by the credit information company Experian, the online trading and investing company Scottrade, the accounting software company Intuit, and Verizon (we were surprised the acai berry people didn't make the cut). In all, America's internet users were flooded with over one trillion ads during the quarter.

Erick Schonfeld at TechCrunch explains that Facebook's strong performance doesn't necessarily mean the company is stealthily transforming social networking into a blaring billboard. Facebook's growing popularity allows it serve more ads on more pages, Schonfeld notes, and the company is also experimenting with social ads that look more like News items shared by friends.

Picture by onlinedesign via Flickr