Hangout API allows developers to extend, enhance and develop collaborative applications that run inside google+ hangouts.

As Google+ team adds more features into hangouts, they also add more capabilities into the api so that developers can build amazing things. Today is the release of version 1.4 of the api with some new features and adding abilities to better control the hangout from any app.

Hangouts API 1.4 includes the following changes

• Determine age restrictions
• Customize and control participants displayed in Hangout on Air (HOA) [more details about video feeds here]
• Select primary participant for the main video
• Detect change of regular hangout to Hangout on Air (HOA)
• Get locale of a hangout participant

More details and documentation about the hangout api 1.4 changes is available here

To get a feel about what is possible through the hangout api take a look at the ping pong hangout game.