To help you discover more interesting content faster and to improve your reading experience, Google Reader added two new features:

• Explore section consolidates "popular items" and "recommended sources" feeds (two ways to find interesting content from all over the Internet). "We use algorithms to find top-rising images, videos and pages from anywhere (not just your subscriptions), collect them in the new Popular items section and order them by what we think you'll like best."
  
• To switch to “personalized ranking” feature - click "Sort by magic" under the "Feed settings" menu of your feed (or folder). Unlike old "auto" ranking, this new ranking’s personalized for you, and gets better with time as we learn what you like best — the more you "like" and "share" stuff, the better your magic sort will be.