With the latest changes, you can now expand your circles, filter emails and contact by circles, and keep all of your contact information up-to-date in one centralized location.
So what does this mean? When you receive an email, with the new Google+ integration will give you’ll be able to see their latest post right there in Gmail, even if they’re not in your circles. This will make it easier than ever to add your Gmail contacts to your Google+ circles.
If you’ve worked long and hard getting your Google+ circles just right, you can filter your email messages by your existing circles. You can see all the emails you’ve received from a specific circle at the click of a button. With the new feature you can also choose to view circle names on emails in your inbox.
Integration with Google+ means that you can keep your contact list up to date based entirely on how each and every user updates their own Google+ profile. You don’t have to worry about doing it manually. Any information you add to your public profile on Google+ will be visible to your friends in Contacts.
You can also now share photos directly from Gmail to Google+. Find out more about how to do that here.