Looking for module like account types, but account types should be roles as well

Hi, I found the "account types" module pretty good, but I really need the account types to be roles as well. A more generic way of putting it; I want a hierarchical system for roles, where a role can have subroles automatically assigned to the user with that role.

A simple, contrived example. Two departments (as roles): "Maintenance" and "Development". We have a set of privileges contained in the "manage site content" role that needs to be shared between these roles. It would be nice to be able to attach this role as a "subrole" to both of them as the alternative would be to either add the privilages in "manage site content" to each of the roles, or manually assign "manage site content" to all user that belong to either "Maintenance" or "Development". A hierarchical roles system of this kind would also play rather nicely with Role delegation, Role Assign and in some ways even Administer users by role. I couln't find a module that does what I need in the module repository. I guess It could be achieved with Organic groups, but OG is inflexible in many ways, a bit more than I need thus introduces unnecessary complexity and does not integrate well with the drupal permissions system in general. I'm asking just to be certain, is the only way to fix this right now to write this module? I could probably do it given enought time (lacking that right now), though I have a lot of other ideas for drupal project and would love not having to spend time on this (as I find the other ideas more exciting:)).