There should be a Can Manage Sharing permission, separate from Can Manage Security

(Bug, To be Fixed , Priority: High, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Security
Summary: Currently, both the Sharing and Security pages hang off of Who Can Manage Security. But conceptually they're separate -- Can Manage Security is about defining the Space, and Can Manage Sharing is about invitations, roles, and deciding who gets to do what.