diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index f8d4057df585fdf8ab3cd4f2fce54dc38515327b..c91a0dcde7b2823dafe00dedc53d4b6796af9b40 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,13 @@
 *SVN*
 
+* Added that respond_to blocks will automatically set the content type to be the same as is requested [DHH]. Examples:
+
+    respond_to do |format|
+      format.html { render :text => "I'm being sent as text/html" }
+      format.rss  { render :text => "I'm being sent as application/rss+xml" }
+      format.atom { render :text => "I'm being sent as application/xml", :content_type => Mime::XML }
+    end
+
 * Added utf-8 as the default charset for all renders. You can change this default using ActionController::Base.default_charset=(encoding) [DHH]
 
 * Added proper getters and setters for content type and charset [DHH]. Example of what we used to do:
diff --git a/actionpack/lib/action_controller/mime_responds.rb b/actionpack/lib/action_controller/mime_responds.rb
index 07bbbb473282ce30865930c5aa00e3ca116b7382..6c721f4ba2a47aa0c73aaa445dee7e607ce9f4e9 100644
--- a/actionpack/lib/action_controller/mime_responds.rb
+++ b/actionpack/lib/action_controller/mime_responds.rb
@@ -108,7 +108,7 @@ def respond_to(*types, &block)
     
     class Responder #:nodoc:
       DEFAULT_BLOCKS = [:html, :js, :xml].inject({}) do |blocks, ext|
-        blocks.update ext => %(Proc.new { render :action => "\#{action_name}.r#{ext}" })
+        blocks.update ext => %(Proc.new { render :action => "\#{action_name}.r#{ext}", :content_type => Mime::#{ext.to_s.upcase} })
       end      
       
       def initialize(block_binding)
@@ -129,7 +129,10 @@ def custom(mime_type, &block)
         @order << mime_type
         
         if block_given?
-          @responses[mime_type] = block
+          @responses[mime_type] = Proc.new do
+            eval "response.content_type = Mime::#{mime_type.to_sym.to_s.upcase}", @block_binding
+            block.call
+          end
         else
           if source = DEFAULT_BLOCKS[mime_type.to_sym]
             @responses[mime_type] = eval(source, @block_binding)            
diff --git a/actionpack/test/controller/content_type_test.rb b/actionpack/test/controller/content_type_test.rb
index 71563ba9a666210c8f28c121f55e4a9319060c31..f2708acc0a3a992bc5a46b982d11ea834cab0a6a 100644
--- a/actionpack/test/controller/content_type_test.rb
+++ b/actionpack/test/controller/content_type_test.rb
@@ -30,6 +30,15 @@ def render_change_for_rxml
     render :action => "render_default_for_rxml"
   end
 
+  def render_default_content_types_for_respond_to
+    respond_to do |format|
+      format.html { render :text   => "hello world!" }
+      format.xml  { render :action => "render_default_content_types_for_respond_to.rhtml" }
+      format.js   { render :text   => "hello world!" }
+      format.rss  { render :text   => "hello world!", :content_type => Mime::XML }
+    end
+  end
+
   def rescue_action(e) raise end
 end
 
@@ -96,4 +105,26 @@ def test_change_for_rxml
     assert_equal Mime::HTML, @response.content_type
     assert_equal "utf-8", @response.charset    
   end
+  
+  def test_render_default_content_types_for_respond_to
+    @request.env["HTTP_ACCEPT"] = Mime::HTML.to_s
+    get :render_default_content_types_for_respond_to
+    assert_equal Mime::HTML, @response.content_type
+
+    @request.env["HTTP_ACCEPT"] = Mime::JS.to_s
+    get :render_default_content_types_for_respond_to
+    assert_equal Mime::JS, @response.content_type
+  end
+
+  def test_render_default_content_types_for_respond_to_with_template
+    @request.env["HTTP_ACCEPT"] = Mime::XML.to_s
+    get :render_default_content_types_for_respond_to
+    assert_equal Mime::XML, @response.content_type
+  end
+  
+  def test_render_default_content_types_for_respond_to_with_overwrite
+    @request.env["HTTP_ACCEPT"] = Mime::RSS.to_s
+    get :render_default_content_types_for_respond_to
+    assert_equal Mime::XML, @response.content_type
+  end
 end
\ No newline at end of file
diff --git a/actionpack/test/fixtures/content_type/render_default_content_types_for_respond_to.rhtml b/actionpack/test/fixtures/content_type/render_default_content_types_for_respond_to.rhtml
new file mode 100644
index 0000000000000000000000000000000000000000..25dc746886c84049487c57a1c095fcabbe72cbe1
--- /dev/null
+++ b/actionpack/test/fixtures/content_type/render_default_content_types_for_respond_to.rhtml
@@ -0,0 +1 @@
+<hello>world</hello>
\ No newline at end of file