ActiveRecord 3.1 - Mass-Assignment Roles (ablogaboutcode.com)

Write up a patch? It may be a little late in the game to be changing APIs, but it might be ok since it's just beta 1.

This month's Communications of the ACM has a good article by Patrick McKenzie on Rails security, and the mass assignment vulnerability in particular.

Chaining the role would make it easier to add the role to inherited_resources, you'd just need to add it to your beginning_of_association_chain