Tab for Google+ by FIPLAB available from the Mac App Store is a ultimate Mac desktop client for all your Google+ needs. Be at the forefront of your social activity from the ease of your menu bar, without the need to open an internet browser window.
Quick, simple, effortless - just how you would expect.
The app is available for free and offers just about every feature plus.google.com offers -- except Hangouts. Upon logging in via your Google account, you'll be greeted with the main sections of the app: Streams, Photos, Circles, Profile and Notifications.
The sections follow suit with the functionality of the website. Streams and Photos curates content from the people you're following. Circles allows you to see your list of circles and the content coming in from each specific one. Lastly, Notifications let's you know what's going on with your account.
Here're a few screens of the app:
You can download free Tab for Google+ app from Mac App Store.