Index: wysiwyg.js
===================================================================
--- wysiwyg.js	(revision 291)
+++ wysiwyg.js	(working copy)
@@ -212,6 +212,19 @@
 };
 
 /**
+ * Removes unwanted 'blank' <p> and <br /> tags from an HTML string.
+ *
+ * Editors sometimes leave tags like <p>&nbsp;</p> when nothing was entered.
+ * This function removes those tags to allow for truly empty fields.
+ *
+ * @param content
+ *  An HTML string to remove tags from.
+ */
+Drupal.wysiwyg.removeBlankTags = function(content) {
+  return content.replace(/^(?:<p>(?:&nbsp;|\s*)<\/p>|<br(?:\s\/)?>(\r)?(\n)?)$/i, '');
+}
+
+/**
  * Allow certain editor libraries to initialize before the DOM is loaded.
  */
 Drupal.wysiwygInit();
Index: editors/js/fckeditor-2.6.js
===================================================================
--- editors/js/fckeditor-2.6.js	(revision 291)
+++ editors/js/fckeditor-2.6.js	(working copy)
@@ -88,7 +88,7 @@
           data = Drupal.wysiwyg.plugins[plugin].detach(data, Drupal.settings.wysiwyg.plugins.drupal[plugin], instance.FCK.Name);
         }
       }
-      return data;
+      return Drupal.wysiwyg.removeBlankTags(data);
     };
     instance.FCK.DataProcessor = new wysiwygDataProcessor();
   },
Index: editors/js/ckeditor-3.0.js
===================================================================
--- editors/js/ckeditor-3.0.js	(revision 291)
+++ editors/js/ckeditor-3.0.js	(working copy)
@@ -79,7 +79,7 @@
     pluginsLoaded: function(ev) {
       // Override the conversion methods to let Drupal plugins modify the data.
       var editor = ev.editor;
-      if (editor.dataProcessor && Drupal.settings.wysiwyg.plugins[params.format]) {
+      if (editor.dataProcessor) {
         editor.dataProcessor.toHtml = CKEDITOR.tools.override(editor.dataProcessor.toHtml, function(originalToHtml) {
           // Convert raw data for display in WYSIWYG mode.
           return function(data, fixForBody) {
@@ -101,7 +101,7 @@
                 data = Drupal.wysiwyg.plugins[plugin].detach(data, Drupal.settings.wysiwyg.plugins.drupal[plugin], editor.name);
               }
             }
-            return data;
+            return Drupal.wysiwyg.removeBlankTags(data);
           };
         });
       }