Gmail is giving an extra feature - People widget
Next to every email message you can now see contextual information about the people in that conversation including recent emails you received from them, relevant Buzz posts, shared documents and calendar events. You also have quick access to a variety of ways to communicate with individuals, start a group chat or schedule a meeting with groups of people.
This is an interesting feature.
But I suggest that Gmail must have a social networking mail box like priority mail box.