The Google+ app has just been updated to add a few bits of functionality and a new notification system. With the previous update we received a new post composition screen that let you add a photo or mood to the post, and this update is putting a "link" option between the two. Tapping on it lets you manually add a URL, although we'd bet most people will be copy/pasting URLs in. On the main UI side, notifications have been redesigned as well. Instead of being hidden underneath the navigation controls in the left slide-in panel, you get a separate notification number between the refresh and settings buttons, that when tapped brings in a full notification-specific panel from the right.
The update also allows for more moderation options in Google+ Communities, which were recently released. You can grab a download of the new Google+ at the Play Store link above.