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@@ -203,7 +203,7 @@
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     #     has_many :people, :extend => FindOrCreateByNameExtension
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     #   end
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     #
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-    # ==== Association Join Models
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+    # ==== Association Join Models
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     # 
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     # Has Many associations can be configured with the :through option to use an explicit join model to retrieve the data.  This
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     # operates similarly to a <tt>has_and_belongs_to_many</tt> association.  The advantage is that you're able to add validations,
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@@ -243,6 +243,24 @@
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     #   @firm.clients.collect { |c| c.invoices }.flatten # select all invoices for all clients of the firm
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     #   @firm.invoices                                   # selects all invoices by going through the Client join model.
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     #
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+    # === Polymorphic Associations
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+    # 
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+    # Polymorphic associations on models are not restricted on what types of models they can be associated with.  Rather, they 
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+    # specify an interface that a has_many association must adhere to.
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+    # 
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+    #   class Asset < ActiveRecord::Base
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+    #     belongs_to :attachable, :polymorphic => true
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+    #   end
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+    # 
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+    #   class Post < ActiveRecord::Base
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+    #     has_many :assets, :as => :attachable         # The <tt>:as</tt> option specifies the polymorphic interface to use.
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+    #   end
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+    #
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+    #   @asset.attachable = @post
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+    # 
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+    # This works by using a type column in addition to a foreign key to specify the associated record.  In the Asset example, you'd need
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+    # an attachable_id integer column and an attachable_type string column.
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+    #
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     # == Caching
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     #
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     # All of the methods are built on a simple caching principle that will keep the result of the last query around unless specifically
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@@ -465,6 +483,7 @@
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       # * <tt>:offset</tt>: An integer determining the offset from where the rows should be fetched. So at 5, it would skip the first 4 rows.
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       # * <tt>:select</tt>: By default, this is * as in SELECT * FROM, but can be changed if you for example want to do a join, but not
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       #   include the joined columns.
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+      # * <tt>:as</tt>: Specifies a polymorphic interface (See #belongs_to).
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       # * <tt>:through</tt>: Specifies a Join Model to perform the query through.  Options for <tt>:class_name</tt> and <tt>:foreign_key</tt> 
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       #   are ignored, as the association uses the source reflection.  You can only use a <tt>:through</tt> query through a <tt>belongs_to</tt>
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       #   or <tt>has_many</tt> association.
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@@ -478,6 +497,7 @@
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       #   has_many :people, :class_name => "Person", :conditions => "deleted = 0", :order => "name"
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       #   has_many :tracks, :order => "position", :dependent => :destroy
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       #   has_many :comments, :dependent => :nullify
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+      #   has_many :tags, :as => :taggable
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       #   has_many :subscribers, :through => :subscriptions, :source => :user
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       #   has_many :subscribers, :class_name => "Person", :finder_sql =>
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       #       'SELECT DISTINCT people.* ' +
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@@ -603,12 +623,14 @@
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       #   is used on the associate class (such as a Post class). You can also specify a custom counter cache column by given that
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       #   name instead of a true/false value to this option (e.g., <tt>:counter_cache => :my_custom_counter</tt>.)
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       # * <tt>:include</tt>  - specify second-order associations that should be eager loaded when this object is loaded.
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+      # # <tt>:polymorphic</tt> - specify this association is a polymorphic association by passing true.
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       #
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       # Option examples:
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       #   belongs_to :firm, :foreign_key => "client_of"
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       #   belongs_to :author, :class_name => "Person", :foreign_key => "author_id"
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       #   belongs_to :valid_coupon, :class_name => "Coupon", :foreign_key => "coupon_id", 
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       #              :conditions => 'discounts > #{payments_count}'
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+      #   belongs_to :attachable, :polymorphic => true
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       def belongs_to(association_id, options = {})
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         reflection = create_belongs_to_reflection(association_id, options)
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