It seems that Facebook are now choosing which 250 friends people are most interested in and only posting those people to the News Feed. This limit has been imposed recently and needs to be manually reset for people to be able to see all of their friends again. Strange I know, but there’s an easy fix:

1. Go to your Facebook home page
2. Scroll down to the bottom of the News Feed and you’ll see the ‘Edit Options’ link on the right hand side. Click it.
3. A popup will appear with a ‘Number of friends’ text box. Update that to 9999 and click ‘Save’.

Whether this limit remains in place permanently is hard to say, but what’s even more worrying is that it seems to include pages that you’re a Fan of… which means that resetting your limit is even more important.