Google Requires People to Use the Google+ Social Network, Gains Ground Against Facebook - WSJ.com

Resistance is futile; you will be +ssimilated, if you use multiple Google services

"Both Facebook and Google make the vast bulk of their revenue from selling ads. But Facebook has something Google wants: Facebook can tie people's online activities to their real names, and it also knows who those people's friends are. Marketers say Google has told them that closer integration of Google+ across its many properties will allow Google to obtain this kind of information and target people with more relevant (and therefore, more profitable) ads."

Google Requires People to Use the Google+ Social Network, Gains Ground Against Facebook - WSJ.com