Today Google released a new video showcasing a brand new UI design - see below.
The new design will revolve around sharing media; photos and videos will take up a much larger portion of your news feed (a small reminder of Facebook Timeline). Sharing across Google's other sites such as Youtube seems to be improved also, with the addition of a dedicated share button in the Google nav bar. Additionally, replacing the static navigation icons currently found at the top of the screen is a customisable ribbon down the left hand side. Said ribbon allows users to change the order of the icons (or even remove them), allowing you to prioritise effectively.
The addition of dedicated hangouts page is new too. Both this screen and the new contact ribbon at the right hand edge of the screen, will help to make starting and participating in hangouts an easier and smoother experience.
Google have already updated their 'learn more' site, so all users should see the update pushed to their own Google+ account shortly.