With the release of Joomla 2.5, the ACL of your Joomla CMS will be more comfortable. You can add new users, user groups or access levels and combine them with each other. You can manage the access control in the User Manager of your Joomla 2.5 Administration. Use the path: "Joomla 2.5 Administration" - "Users" - "User Manager"
That remains and that is new!