I'm curious how much work/how feasible it would be to extend Drupal to have a more flexible based group permissions system. I understand that you can setup "user roles" and assign a user a role, then define that roles permissions. However, this is very very limited.

I'd like to see a system where multiple groups can be created, each group has it's own permission settings. Then a user can be a member of multiple groups.

A new admin section might be needed, where the site admins assign a user to a group. Or, each group might be able to have it's own administrator, who has authority to add or delete users from their own group.

In addition, the main site admin could juggle users around into/out of various groups as they saw fit.

In addition, I'd like to see the group permissions extended where users could create a group. Then, the users could define what nodes or content or calendar/events, etc... can be accessed by the public at large, or by the user assigned groups.

This would be basically extending drupal more towards the PHProjekt style of user/group permissions. Instead of dwelling in the land of CMS, moving more into the land of CMS/GroupWare based systems. A lot of the basics to Drupal would lend itself well to expanding into GroupWare, just none of the controls exist to manage this.

Any thoughts? Basically, I want to use PHProjekt for my use, but it's too GroupWare oriented, and Drupal is too CMS and not enough GroupWare oriented.