Features, features, features
Google Apps for Business support
If enabled by a Site Administrator, content can now be publicly shared with their own circles and employees.
Direct access to photos and videos from Google Drive
Now photos and videos that are stored within Google Drive can be viewed and shared within the Google+ app. For photos on Google Drive, you can use the same automatic filters and optimizers that are available for photos that you upload directly within Google+.
Easy switch between accounts and page
You can easily switch between multiple accounts and/or pages, much like the way Gmail works right now. Thankfully, you no longer need to log out and sign in again to access a different account.
Google+ can now be controlled to specify with whom one’s own site is shared. The choices are between groups (family members, individuals, etc).
Well, it wasn’t only a certain amount of time until Google deleted their Google Messenger service and replace it completely with Google Hangouts. With the most recent updates, Google+ Messenger conversations can be downloaded and saved via Google Takeout.
Download: Google+ for Android
[Update: 15.08.2013, 06:38
The update is now being rolled out and we’ve put the APK file for version 4.1 of Google+ for Android online for you to download at your pleasure: Download APK