The excitement surrounding yesterday's Facebook v3.0 update rapidly turned into frustration for many users after both of the app's new features ended up not working exactly as described, which has forced the company to issue a fix in less than 24 hours.
Yesterday's v3.0 update added push notifications to the Facebook app and also added a welcomed contact syncing feature, but sadly, the push notifications turned out to be a shell of themselves without the vibrate and sound portion working, and contact syncing caused other apps that accessed the address book to stop working entirely.
Facebook issued a new update this morning, v3.1.1, that fixes the nasty contact syncing bug, but they have failed to address the push notification issues.
Feel free to update your Facebook app knowing that it at the very least won't break anything, it just won't work exactly as you had hoped.