SearchForecast recently published insights from their Premium AdSense Publishers Survey.
The data was collected via online surveys with 40 premium AdSense publishers in October 2010.
Respondents were selected by SearchForecast for having a Google PageRank of 4/10 and higher, and an Alexa rank of less than 100,000.
Additionally, 60% of the AdSense publishers had run AdSense ads on their site for 3+ years, while 30% had been running AdSense for 1-3 years.
Findings in the report include how 20% of AdSense publishers have never heard from an alternative ad network, and 70% of AdSense publishers are willing to switch to another network for better payouts.