Since the feature you?ve noticed was part of a temporary test, we?ve removed it from publishers? accounts.
To obtain similar functionality, however, we encourage publishers to sign up for Google Sitemaps, which will provide reporting details on a site?s crawl status, common words that are linked to the site?s pages, and the top search queries on Google that are driving traffic to that website.
For more information, please visit http://www.google.com/trysitemaps.
As you know, we?re always working on new features for AdSense. I?d encourage you to keep an eye on the AdSense blog, where we?ll release details on new features as they become available. You can find the blog at http://adsense.blogspot.com