Desirable
 - accept the free/busy information as a POST
 - more translations of the administration interface
 - translations of the website.
 - the ability to see a better list of event data in the admin interface

Important
 - Add ability to delete users & collections
 - Expose the Admin option to maintenance by admins.
 - Implement support for the ACL method
 - Implement support for updating the acl via PROPPATCH
 - Implement the DAV::acl-principal-prop-set report from RFC3744
 - Implement the DAV::principal-match report from RFC3744
 - Implement the DAV::principal-search-property-set report from RFC3744
 - Implement draft-desruisseaux-caldav-sched specifications.

Minor
 - Check for read-acl privilege to PROPFIND acl
 - Check for read-current-user-privilege-set to PROPFIND current user privs.