The latest small changes noticed by devoted fans of the Android app include the addition of a fifth bottom bar option. The "Collections" tab is also renamed as "Discover," just as you’ll find if you directly access the Google+ mobile website.
While the "Profile" tab basically doesn’t need an introduction or explanation, allowing you to more easily get to your personal info, change it, as well as create communities and collections, the "Discover" feature is different from "Collections" as far as functionality goes. Instead of promoting featured content first, the tab lets you discover more stuff from accounts you follow, while hiding most featured collections behind a "View all" button.
Left: new. Right: old
The new bottom bar has started showing up over the last couple of days as a server-side update affecting most recent Google+ versions. Again, this is not a major change, and there’s obviously no big visual overhaul coming so soon after the last one, but if you’re a fan, you’re likely to appreciate the small things.