Contacts (contacts.google.com) is the latest google product to get Google+ integration and so the social features. Watch your contacts details appear on in his/her G+ profile (of course it is private and only visible to you).
Google contacts with Google+ features
When you are a Gmail user and manage your contacts with google contacts (phone, email, address), with this new G+ integration you can quickly, securely and privately see these contact information under your contacts Google+ profile (refer image below).
Here is how the above contact data appears under google contacts