Android users will have noticed an update to the Google+ app in the last week which bumps up the version number from 6.4 to 6.5. The main addition follows a trend which Google started a couple of months back: Splash screens.
Splash screens are used to show the user that something is happening when you tap on an app icon. Without a splash, there could be a few milliseconds delay between tapping the app icon and having the content displayed on the screen. Splash screens are somewhat controversial in a way that it is a false sense of speed, but I would rather look at a pretty icon than my app drawer while the app loads.
The Google+ splash screen is similar to the rest of Google's suite of services in that it shows the app's icon and a monochrome variant of the Google typeface against a blank background. It's clean and minimalist.
There is probably a myriad of the usual bug fixes in this release, but we don't know for sure as the changelog is rarely updated.
Source: Google+ on Google Play