Google released a People Widget in Gmail recently.
When you access into your Gmail account, and when you have friend who you is in your contact is online, you will see the message:
New! People widget
You do not currently share a photo with recipients
Update your photo…
Some actions, …. or can be found in the More menu in the toolbar…
A screen shot like the following:
You can see since LinkedIn provides convenient connection method you can easily connect with your friends who you have added in your LinkedIn account.
You can check individual contact information by clicking the contact’s name in the People widget list to open an expanded view of information about that contact.
You can also interact with a group by using group chat.
About more detail, please read Google’s help information:
About the people widget
Email is just as much about the people you communicate with as it is what you’re communicating about. The Gmail people widget, located on the right-hand side of your messages, shows you contextual information about people you’re interacting with in Gmail.
You can communicate with individual contacts easily through the people widget, or just use it to find basic information. Simply click on the contact’s name on the right side. From there, you’ll see:
Information about your contact, which may include information such as their email address or occupation. This information comes from your account’s Contact Manager.
Recent buzzes your contact has posted that are visible to you
Recent email your contact sent you
Google Calendar events if your contact’s Calendar is shared with you
Google documents shared with both you and the contact