It is all about sharing stuff you liked online with your friends. Google has silently (but obviously not that secretly) released this Social Bookmarking tool which allows you to share the stuff you liked online – be it any post, video or bookmark. Every shared item will be visible to rest of the world via specific URL linked to your Google account.
Google Shared Stuff can be easily added by using Bookmarklet for your browser.
It looks more into Social Bookmarking space and when it involves Popular tag for some of posts, that mean it is somewhat like Digg – attracting more users by different means, for contribution.
(via)