Google Apps Directory Sync is the latest improvement to Google Apps brought over from Google's Postini security and archiving services, and lets businesses and schools with an LDAP user directory system like Microsoft Active Directory or Lotus Domino transition more quickly and smoothly to Google Apps. Instead of manually maintaining a separate user account directory in Google Apps, this utility lets Google Apps tap into an existing repository of user account information.

This new utility is a software component included at no additional cost with Google Apps Premier, Education and Partner Edition customers, and helps maintain security by running behind the firewall and pushes directory information to Google Apps – including mailing lists, groups and user aliases – to match the organizational schema in the LDAP system, announced Google Enterprise blog.

More info: Google Apps Directory Sync