Change to node output socket drawing: Instead of always drawing only the socket label for outputs, leave this check up to the socket type draw function. This gives custom node scripts more flexibility in

how to draw socket values by allowing buttons on output sockets as well.

http://wiki.blender.org/index.php/Extensions:2.6/Py/API_Changes#Python_Node_Output_Drawing

release/scripts/templates_py/custom_nodes.py

@@ -40,7 +40,7 @@ class MyCustomSocket(NodeSocket):
 
     # Optional function for drawing the socket input value
     def draw(self, context, layout, node, text):
-        if self.is_linked:
+        if self.is_output or self.is_linked:
             layout.label(text)
         else:
             layout.prop(self, "myEnumProperty", text=text)