Many people these days use several social apps … like twitter, facebook etc. Friendfeed is a place you can go to see all your friends and postings from all those services and make comments or reply to the posts.
Stumbleread treats your Friendfeed as the left column and any post you click on in that column is displayed in the main page (including the video link or web gage mentioned in the post) .
Really very handy … keeps you from opening new tabs to view items. I Like it!