Google have announced that Google+ will become a Google Apps core service. This means that Google+ will be included in most customers’ existing Google Apps agreements and will have the same technical support and service level commitments as any other core service.
As part of this transition, current Google+ users must migrate the service to the new user interface announced last November. The new version of Google+ qualify for the main services and incorporates various improvements in usability, using Google+ simplifies and facilitates navigation. Likewise, significant changes will be made in Events, Hangouts and Hangouts on Air (HOA).
In the coming weeks, Google will automatically migrate all Google+ user accounts to the new user interface. Initially, they will be offered the option to keep the old version, but later this possibility no longer be available.
More information: Transition Guide