The increase from 2010 to 2011 was primarily due to an increase in traffic, monetization improvements including new ad formats, global expansion, and added Google Network members, as well as an increase in the average cost-per-click paid by advertisers.

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Google Mobile Ads, Millennial Media and other mobile ad networks will grow faster than the iAd Network.

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"Google is helping to validate the space, " says Jameson Hsu, chief executive of in-game ad network Mochi Media.

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