Google+ is the social extension to Google. More than a social network Google+ effects your search rankings too.
Use Circles to Target Specific Groups
Separate weekday versus weekend guests, business versus leisure guests, family versus couples, and so on
Have Real time discussions with your guests through video conference in Google+ Hangout. Even Barack Obama has hosted a Google+ Hangout.
Google+ gives you invaluable information about your audience. Connect your webmaster and Adwords accounts to your profile to gain valuable information showing the age, gender, and geo-location of those in your circles. You can also see content that guests have shared, reposted, and +’d most often through Google Ripple.
Using information provided through your Google+ account can:
Stronger integration between Google+ and Google Places thanks to check-in offers now available through Google Places