Some publishers over at WebmasterWorld and Google AdSense Help forums are saying they are now seeing an invitation within their Google AdSense interface to join the User First beta program.
It looks like Google AdSense is awarding publishers that have a user first approach with “early access to new features designed to help boost your revenue and provide your visitors with better ad experiences.” The help document says:
Welcome to AdSense’s User First beta program. You were invited to this beta program because you offer your visitors a good web experience, e.g., your pages are fast-loading or your users are happy with the ad layout on your site. With this beta, by meeting certain requirements, you’ll get early access to new features designed to help boost your revenue and provide your visitors with better ad experiences.
In short, Google will invite those publishers that have fast sites, user friendly ad layouts and high ad satisfaction scores to this program. You will also gain access to this user first score card to see how well you scored and where you can improve:
You can learn a lot more about this program over here.
Forum discussion at WebmasterWorld and Google AdSense Help.