I kept track.
66 - End of 2009
186 - End of 2010 - 2.8 times growth
231 - March 1, 2011 -
Are we headed for 550 by year's end, and will this be more difficult to manage? I think it will become a lot of work eliminating the chaff, for those who enable them. One might have to adopt an "enable" philosophy, as opposed to a "disable" philosophy.
Google AdSense Certified Ad Networks are growing like gangbusters.