Publishers using Google's Ad Exchange generated an average of 188% more revenue compared to those using indirect sales

"To see how what kind of effect the growth of the Exchange was having on its participants, we undertook an analysis that quantified the Exchange’s impact on participating publishers’ bottom lines. Today, we’re publishing a white paper that shows that when publishers make ad space available in the Ad Exchange, and the Exchange wins the auction, publishers generate, on average, 188% more revenue compared with indirect sales to ad networks and other third-party buyers. Over millions of impressions, this can make a huge difference to publishers’ advertising revenues, which is great for the web as a whole.
This 188% increase is a result of two key trends that we’re seeing:
Demand for publishers’ inventory is increasing as more AdWords and Google Display Network advertisers start running display campaigns, get great results and invest further. For example, display advertising spend among Google’s largest 1,000 advertisers increased 75% in the past year. Agency trading desks and new third-party technology providers are also running more display ads through the Ad Exchange. And real-time bidding—which enables advertisers to tailor their bids and ads in real time to buy the ad space they value the most—continues to be a major draw, now accounting for 56% of buyers’ spend.
We’re seeing publishers increasingly leverage the Ad Exchange’s “dynamic allocation” to sell their inventory. Via dynamic allocation, the Exchange compares—in real time—the value of the highest-paying ad in the Ad Exchange with any ads from other sources (such as ad network deals) and chooses the highest paying one. The Ad Exchange only serves ads when it can offer a higher price for ad space. Of course, publishers are in complete control of which networks they allow to bid, what ads can appear on their sites and which ad space they make available."
Source:  Google blog, 16th January 2011