Article.rb

class Article < ActiveRecord::Base

	has_one :publication, :as => :publicationable
	accepts_nested_attributes_for :publication

end

ArticlesController

def new
  	@article = Article.new
  	@article.build_publication
  end

new.html.erb

<%= form_for [:admin, @article], :html => { :class => "lalign" } do |f| %>

  <%= f.fields_for :publication do |builder| %>
    <div class="clearfix">
      <%= builder.label :name %>
      <div class="input">
        <%= builder.text_field :name, :class => "span9" %>
      </div>
    </div>
  <% end %>

<% end %>

Publication.rb

class Publication < ActiveRecord::Base

  belongs_to :publicationable, :polymorphic => true

end