The latest version of the Google+ app for Android lets you copy the text of a post, copy comments, quickly reply to comments, translate posts and comments.
While the new features are useful, I don't see why you can't select some of the text and copy it. The Google+ app still doesn't support sharing intents. I assume that apps like Google+ and Facebook want to force users to stick to their own sharing features.
The Google+ app actually supports sharing intents, but only for your photos. The sharing interface looks different and it includes Google+ options. Google+ Photos has a new icon, it's now called "Photos", it includes photos and videos stored on your device, an Auto-Awesome section and is poised to replace the standard Android Gallery.
There's also an updated notification sidebar that shows the notifications you've read in a new section: "previously read". The interface is cleaner, but it's more difficult to hide the sidebar.
If you can't update to the new Google+ version, blame staged rollouts and download the APK file from here.