Sean Purcell, a product manager at Google, announced through a post on Google+ that contact information users have for their contacts in Google Contacts will now be displayed on the contacts' About page on Google+. The info, as you can see in the picture Purcell provided above, is only visible to you, and only if you already have that information stored in Google Contacts.
Though the feature was supposed to debut yesterday, I can't seem to get the 'Details from Google Contacts' section to show up on my friends' Google+ pages. Purcell stated in the comments to his post that the roll-out of the feature was not yet at 100%.
It won't make much difference to me when the information finally does show up in Google+. If I'm looking for a friend or family member's phone number or address, I'll be using my Android phone, which has been synced with my Google Contacts since I bought it two years ago. However, some Google+ users already put their phone number and other personal information up for people in certain circles. Purcell points out, replying to a comment on his original post, that changes to a person's personal information on their Google Profile already sync automatically to Google Contacts. "If your friends have Android ICS [Ice Cream Sandwich] with the Google+ app installed, your profile info will sync to their phones too," wrote Purcell
A fantastic feature. It's always hard to keep up with everyone's contact info, and being able to know everyone in, say, my family and close friends circles will always be synced with my up-to-date phone number and address makes things easy. Then again, it might sound a little too easy: I know it's just a matter of time before the privacy pedants will show up to ruin our interconnected party.