Whenever Facebook launches a new design, things get misplaced. If your favorite way to browse Facebook is to browse your News Feed chronologically, here's how to fix it:
Login to Facebook at http://www.facebook.com/#! instead of just facebook.com, and click "Most Recent" at the top right.
Scroll to the bottom and click "Edit Options". In the bottom left of the popup under "Number of friends", enter "5000" to see more recent updates in your feed.