Here is the official changelog for Facebook for Android version 1.9:
- Improved performance and various bug fixes.
- More messaging features like creating group messages and adding friends to existing group conversations.
- Shortcuts to share photos and messages right from your home screen.
The first point is straightforward. The second one refers to how Facebook for Android version 1.9 comes with some of the messenger features found in the standalone Messenger app, including: Mobile/online status, being able to add people on the fly after you’ve already started a group conversation, and having your contact list sorted in the order of people you interact with most frequently.
From the other reports you get the impression that the update is all you need but I found that I had to add the new shortcut icons to my home screens (they are listed under Apps).
- Facebook for Android version 1.9 is out (zdnet.com)
- Facebook Updates Android App: 1.9 Adds Photos, Message Sharing From Home Screen (techcrunch.com)
- Facebook for Android gets direct camera, messaging shortcuts (electronista.com)
- Facebook For Android Updated To v1.9; Brings Performance Improvements and New Shortcuts (techie-buzz.com)