A Google AdSense blog post from last week was the first time Google told us a number of how many AdSense publishers they have. Google said they have "over one million publishers" in their network.
Google, I believe, has never given a size of their publisher network, outside of revenue earned as reported in their financial reports. But I do not believe they ever told anyone how large, in terms of the number of publishers, the AdSense network is.
A WebmasterWorld thread has some publishers saying they are shocked Google has so many publishers. Honestly, does one million sound like a lot? I am not sure. What do you think?
Forum discussion at WebmasterWorld.

Comments:
Jim
04/26/2010 12:47 pm
Did someone win a prize for being the one millionth? Like say a Nexus One?
No Name
04/26/2010 03:00 pm
For Google 1 million does not sound large at all. I wonder how many websites are out there in total. I would ask Google how many of those publishers are really active. I bet only 30% of those 1 million actually have traffic to show for. Not sure where I got 30% but on Monday morning sounds about right :))
Michael Martinez
04/26/2010 08:29 pm
I think Amazon passed the 1 million mark many years ago. This is not, in my opinion, a large number given the size of Google's market visibility.
Darrin Ward
04/27/2010 03:05 am
1 million seems very low to me, to be honest. And I bet that this goes by the 80/20 rule i.e. 80% of the traffic/revenue comes from 20% (200,000) of the publishers. I wonder what the average number of sites per publisher is. I bet it's 5+.