I'm just starting a new app and I'm using Rails 3.0.3
I have the typical admin and customer name spaces with no namespace for all public areas and I have a typical OO approach for my controllers as follows

In their most basic form the controllers look like this

class ApplicationController < ActionController::Base
before_filter :authorize, :except => :login

end

class PublicController < ApplicationController

protected #Protected methods available to all descendant controllers

#This is a public controller so no authorization is necessary def authorize end

#Other methods that need to be made available for public controllers to be added here ... end

class CustonerController < ApplicationController

protected #Protected methods available to all descendant controllers

#This is a customer controller so authorize as a customer #TODO def authorize end

#Other methods that need to be made available for public controllers to be added here #TODO def current_customer end ... end

And again similarly for the admin controller

class AdminController < ApplicationController

protected #Protected methods available to all descendant controllers

#This is a customer controller so authorize as a customer #TODO def authorize end

#Other methods that need to be made available for public controllers to be added here #TODO def current_customer end ... end

My first admin controller, which is a section for customer maintenance, ath the moment is a standard scaffolded controller with the following exceptions
redirect_to and :location paths/declarations take into account the namespace for admin e.g. redirect_to admin_customers_path
plus the important class declaration and the relevant changes have been made to the views to take into account the admin namespace

class Admin::CustomerController < AdminController

Controller for customer administration

... end

Now if I navigate to myapp/admin/users I would expect to see a list of all users but instead I get an error
Started GET "/api/users" for 127.0.0.1 at Sun May 15 15:04:44 +0100 2011

AbstractController::ActionNotFound (The action 'show' could not be found for AdminController):

Rendered /home/jamie/.rvm/rubies/ruby-1.8.7-p302/lib/ruby/gems/1.8/gems/actionpack-3.0.3/lib/action_dispatch/middleware/templates/rescues/unknown_action.erb within rescues/layout (0.5ms)

This works fine in Rails 2.3.5 -> 2.3.8 not tested under other 2.3.x versions.
there is very obviously a fundamental change in the way controller classes behave differently to normal OO rules in Rails 3.0.3 and I have to ask what is going on? and will there/is there a fix for this?

Cheers

James