The Camera icon, as you may expect, allows you to take pictures that are immediately uploaded to Facebook. The Messenger icon seems to take the place of the dedicated Messenger app. It allows you to receive push notifications for all messages, start group messages, and add recipients to existing group messages.
Other than that, the update adds, as per usual, improved performance and various bug fixes. You can head on over to the Google Play store now to grab this update.
Facebook for Android