The Google AdSense Blog announced that they have released a new feature to communicate with AdSense publishers. We reported on this feature a while back, when it was still in beta. But now it appears to be live to everyone.
If you've logged in to your account today, you've probably noticed the new 'Recent messages' section in your AdSense account. We're happy to let you know that this is your personal inbox where we'll send you customized optimization tips. More specifically, our system will automatically analyze your account and ad settings. Based on these findings, you'll receive a notification each month in your AdSense account if there are changes you can make to improve your overall AdSense performance.
A WebmasterWorld thread has tons of comments from publishers.
Some like the optimization reports but many do not.
To be honest I don't think these new tips are entirely helpful and are one-sided to being beneficial to Google.
Forum discussion at WebmasterWorld.