I just launched Canard 0.3.1. Canard adds role based authorization to your Rails applications. Extending the popular CanCan and RoleModel Rubygems Canard lets you define abilities for roles under your app directory making authorization a first class citizen in your application. Canard also adds some simple scopes for finding users based on their roles.

Canard was extracted from an existing application and has been used in several production applications so should be pretty battle hardened.