Permission Sets became generally available for orgs in the Winter ‘12 release. Permission Sets allow administrators to provide individual permissions in conjunction with profiles to enable access for certain users on an ad hoc basis, thus reducing a growing and unmanageable number of profiles in a Salesforce org.
The Permissioner dramatically reduces the time and frustration involved with assigning and revoking permission sets assignments to multiple users. Using a simple interface, administrators can select one or more permission sets to assign to one or more users at a time. When a permission set is selected and users are searched, only those users not already assigned to it will display in the list. This is useful when trying to assign more than 1000 users. With The Permissioner, life is made easy by assigning a permission set to as many users as needed from one intuitively simple screen.