Rails - Jun 2006 - Most recent detail record for master records - what''s the best way to do this?

I''m trying to figure out the best way to display some summary
information in
my app (an article submission database for writers), and I''m not quite
sure
how to get ActiveRecord to give me what I want. 

Here''s what the relevant part of my data model looks like:

-----------------------
class Market < ActiveRecord::Base
  has_many :submissions
  has_many :articles, :through => :submissions
end

class Article < ActiveRecord::Base
  has_many :submissions
  has_many :markets, :through => :submissions
end

class Submission < ActiveRecord::Base
  belongs_to :market
  belongs_to :article
  has_many :actions
end

class Action < ActiveRecord::Base
  belongs_to :submission
  belongs_to :article , :through => :submissions
  belongs_to :market , :through => :submissions
end
-----------------------

The two things I''d like to accomplish are:

- A list of the most recent Action for each Submission associated with a
given Article
- A list of the most recent Action for each Article associated with a given
Market

All of my tables have created_at and updated_at fields, so the concept of
"most recent" is there in my database. But I''m not sure 100%
sure my
associations are correct, nor am I sure what the best way is to get back the
data I need.

Can anyone help? Thanks in advance!

-- Tammy