'Download as' script

IPython/html/static/notebook/js/menubar.js

@@ -129,10 +129,6 b' define(['
             that._nbconvert('html', false);
         });
 
-        this.element.find('#download_py').click(function () {
-            that._nbconvert('python', true);
-        });
-
         this.element.find('#download_html').click(function () {
             that._nbconvert('html', true);
         });
@@ -308,6 +304,16 b' define(['
         this.events.on('checkpoint_created.Notebook', function (event, data) {
             that.update_restore_checkpoint(that.notebook.checkpoints);
         });
+        
+        this.events.on('notebook_loaded.Notebook', function() {
+            var langinfo = that.notebook.metadata.language_info || {};
+            that.update_nbconvert_script(langinfo);
+        });
+        
+        this.events.on('kernel_ready.Kernel', function(event, data) {
+            var langinfo = data.kernel.info_reply.language_info || {};
+            that.update_nbconvert_script(langinfo);
+        });
     };
 
     MenuBar.prototype.update_restore_checkpoint = function(checkpoints) {
@@ -340,6 +346,31 b' define(['
             );
         });
     };
+    
+    MenuBar.prototype.update_nbconvert_script = function(langinfo) {
+        // Set the 'Download as foo' menu option for the relevant language.
+        var el = this.element.find('#download_script');
+        var that = this;
+        
+        // Set menu entry text to e.g. "Python (.py)"
+        var langname = (langinfo.name || 'Script')
+        langname = langname.charAt(0).toUpperCase()+langname.substr(1) // Capitalise
+        el.find('a').text(langname + ' (.'+(langinfo.file_extension || 'txt')+')');
+        
+        // Unregister any previously registered handlers
+        el.off('click');
+        if (langinfo.nbconvert_exporter) {
+            // Metadata specifies a specific exporter, e.g. 'python'
+            el.click(function() {
+                that._nbconvert(langinfo.nbconvert_exporter, true);
+            });
+        } else {
+            // Use generic 'script' exporter
+            el.click(function() {
+                that._nbconvert('script', true);
+            });
+        }
+    };
 
     // Backwards compatability.
     IPython.MenuBar = MenuBar;

IPython/html/templates/notebook.html

@@ -105,7 +105,7 b' class="notebook_app"'
                         <li class="dropdown-submenu"><a href="#">Download as</a>
                             <ul class="dropdown-menu">
                                 <li id="download_ipynb"><a href="#">IPython Notebook (.ipynb)</a></li>
-                                <li id="download_py"><a href="#">Python (.py)</a></li>
+                                <li id="download_script"><a href="#">Script</a></li>
                                 <li id="download_html"><a href="#">HTML (.html)</a></li>
                                 <li id="download_rst"><a href="#">reST (.rst)</a></li>
                                 <li id="download_pdf"><a href="#">PDF (.pdf)</a></li>

IPython/kernel/zmq/ipkernel.py

@@ -75,6 +75,8 b' class IPythonKernel(KernelBase):'
                      'codemirror_mode': {'name': 'ipython',
                                          'version': sys.version_info[0]},
                      'pygments_lexer': 'ipython%d' % (3 if PY3 else 2),
+                     'nbconvert_exporter': 'python',
+                     'file_extension': 'py'
                     }
     @property
     def banner(self):