To sign-up for Google+, people can visit Google.com/+
The Circles feature allows users to selectively share information with different groups of people. You drag-and-drop contacts into self-created Circles of friends, family, co-workers, etc. S
Some other primary features of Google+ include: Hangouts, live group video chat with up to 10 people; Stream, the place to see updates from contacts in Circles; and Mobile, location sharing, group messaging and the option to immediately upload pictures taken on your Android device.
In addition to today’s consumer launch of Google+, additional features and enhancements were announced. They include: Enhanced Search in Google+, Hangouts from your Android device, streamed Hangouts On Air and Hangouts with extras, so you can easily collaborate with others through video chat using Google Docs or a sketchpad.
The Developer Preview of the Hangouts API, enables you to add your own experiences to Hangouts and instantly build real-time applications, just like their first application, the built-in YouTube player.