google-api plus get - Is there already a Google+ API?
The official Google+ API can be found at: http://developers.google.com/+/api/
I would like to know if there is already a Google+ API available to the developers. I have not yet found something?
The API is now here available: https://developers.google.com/+/
Google just announced the developer's page
I think that you'll find this article a good read.
Google Plus doesn't have a public API yet, nor has it announced when one will be available. But if you want to find out about future developer opportunities, Google has a mailing list you can sign-up for to receive more information in the future.
Taken from article linked above.
The API itself is there - it's restful, and requires a client library for each language in order to be used.
Here is one for Java: Googl-plus-java-api