"Many of you, like me, use Google Contacts to manage your personal address book (contacts.google.com). If that's the case, then starting today we'll include this contact info on your friends' Google+ profiles -- for your eyes only, of course," Google's Sean Purcell wrote
"This way, if you have your roommate's new phone number in Google Contacts, it'll also be available when you stop by his profile. Just look for the new "Details from Google Contacts" section," he explained.
The screenshot does the best job at explaining the new feature. It's a rather useful addition and an obvious one at that. All of the data was already linked to your Google account, but because it was in two different services, it had to stay separated. That is no longer the case, which is what people probably expected anyway.
The feature only works for the people you have in your Google Contacts, of course, and that's likely not everyone you know on Google+. Then again, plenty of people add contact information, even phone numbers and email addresses to their Google+ profiles for their friends to see.
It's interesting to note though how much trouble Google has had to go through to add this basic functionality in Google+, getting a lot of people upset over the privacy changes, all while Facebook has been able to grab all the contact data from Gmail, Yahoo Mail, Hotmail and so on which users were more than happy to provide.