Facebook 3.1 for BlackBerry adds two new features
The last Facebook for BlackBerry update added BBM integration to the social networking site
The other feature added is the addition of "Facebook Groups" to the app. This feature helps you stay connected to the various groups that you belong to. From your BlackBerry, you will be able to post updates, comments or add media like video or music. Check out the profiles of members in the same group as you, and be alerted via a notification when a group member makes an update.
The Facebook for BlackBerry 3.1 app is a free download from BlackBerry App World and if you don't see the update there, wait a day. According to BlackBerry's own blog, it can take 24 hours for a new app or update to hit App World.