Google+ is a new social networking site and Google+ Hangouts is a feature supports real time video communication among up to 10 participants run inside browser.
Google+ just released its Google+ Hangouts API Developer Preview at 14 December 2011 which introduced JavaScript interface that enables our apps to interact with the Hangouts stuff, such as list out the participants, controlling some aspects of user interface, sharing data between our created apps. Currently Hangouts API is in developer preview release to collect the feedbacks from developers and it is subjected to change.
Link to Google+ Hangouts API: https://developers.google.com/+/hangouts/reference
