Opening up Google Apps Marketplace beyond Apps administrators
This launch gives the ability for Google Apps admins to open up the Google Apps Marketplace (GAM) to people from their organization to directly find and use 3rd party applications that integrate with Google Apps.
Admins will be able to allow the installation of any GAM apps, or they can choose to customize which apps are made available to their domains. Admins can also turn the feature off altogether if they so choose.
Note: This feature will be defaulted to allow users to install any GAM apps at launch to Rapid release domains (excluding K-12 EDU domains, where it will be defaulted off). Admins from Scheduled release domains will see the Admin console controls for this feature with Rapid rollout, and can disable it if so desired prior to Scheduled launch. Users from Scheduled release domains who try to install an app from GAM prior to the Scheduled rollout will be prevented from doing so and will receive the following error message: You do not have privileges to install this application. Please contact your domain admin.
Google for Work blog post