The feature is called the Ad Review Center. Users can approve or disapprove of ads before they go into the feeds.
To do so, login to your AdSense account. Then look for the Ad Review Center in the 'Competitive Ad Filter' section under the 'AdSense Setup' tab. Choose the Client-ID starting with ca-feed-pub.
You'll have to put your ads on hold for 24 hours before you can filter through them. During that time, no ads will be served to your feeds, but afterwards you can go through the ad approval process.
Meet Your Favorite Search Engine Watch Contributors
Many of SEW's leading expert contributors will be at ClickZ Live, the new online and digital marketing event kicking off in New York (March 31-April 3). Hear from the likes of: Thom Craver, Josh Braaten, Lisa Barone, Simon Heseltine, Josh McCoy, Lisa Raehsler, Greg Jarboe, Dan Cristo, Joseph Kerschbaum, John Gagnon, Eric Enge and more!