Google is launching their answer to Facebook tomorrow and it is called OpenSocial. The URL for the site opens then.
"OpenSocial is a set of three common APIs, defined by Google with input from partners, that allow developers to access core functions and information at social networks:
Profile Information (user data)
Friends Information (social graph)
Activities (things that happen, News Feed type stuff)
Hosts agree to accept the API calls and return appropriate data. Google won’t try to provide universal API coverage for special use cases, instead focusing on the most common uses. Specialized functions/data can be accessed from the hosts directly via their own APIs.
Applications can have full functionality on profile and/or canvas pages, subject to the specific rules of each host. Facebook, by contrast, limits most functionality to the canvas page, allowing a widget on the profile page with limited features.
OpenSocial is silent when it comes to specific rules and policies of the hosts, like whether or not advertising is accepted or whether any developer can get in without applying first (the Facebook approach). Hosts set and enforce their own policies. The APIs are created with maximum flexibility."