Gregor,
Intermedia doesn't provide any permissioning AFAIK. However, in the client projects I worked on at aD we used Intermedia and for permissioning we used the object permissions that OpenACS provide.
We ended up with a SQL statement that selects ACS objects that have an intermedia index match (we used the contains stored procedure in a where clause) and for permissioning we added a where clause with the permission_p stored procedure.
In the ShareNet system we built an advanced search that allowed you to filter objects on their ratings, their modification and creation date, and their categorization. As a bonus Intermedia allows you to check for similar spelling (fuzzy matching).
