Index: Classes/Controller/ReviewController.php
===================================================================
--- Classes/Controller/ReviewController.php	(revision 2842)
+++ Classes/Controller/ReviewController.php	(working copy)
@@ -113,6 +113,17 @@
 	protected function initializeAction() {
 		parent::initializeAction();
 
+		if (tx_Workspaces_Service_Workspaces::isOldStyleWorkspaceUsed()) {
+			$message = t3lib_div::makeInstance(
+				't3lib_FlashMessage',
+				$GLOBALS['LANG']->sL('LLL:EXT:workspaces/Resources/Private/Language/locallang.xml:warning.oldStyleWorkspaceInUser'),
+				'',
+				t3lib_FlashMessage::WARNING
+			);
+
+			t3lib_FlashMessageQueue::addMessage($message);
+		}
+
 		$this->pageRenderer->loadExtJS();
 		$this->pageRenderer->enableExtJSQuickTips();
 		$this->pageRenderer->enableExtJsDebug();
Index: Classes/Service/Workspaces.php
===================================================================
--- Classes/Service/Workspaces.php	(revision 2842)
+++ Classes/Service/Workspaces.php	(working copy)
@@ -400,6 +400,28 @@
 		}
 		return $permittedElements;
 	}
+
+
+	/**
+	 * Trivial check to see if the user already migrated his workspaces
+	 * to the new style (either manually or with the migrator scripts)
+	 *
+	 * @return bool
+	 */
+	public static function isOldStyleWorkspaceUsed() {
+		$oldStyleWorkspaceIsUsed = FALSE;
+		$cacheKey = 'workspace-oldstyleworkspace-notused';
+		$cacheResult = $GLOBALS['BE_USER']->getSessionData($cacheKey);
+		if (!$cacheResult) {
+			$where = 'adminusers != "" AND adminusers NOT LIKE "%be_users%" AND adminusers NOT LIKE "%be_groups%" AND deleted=0';
+			$count = $GLOBALS['TYPO3_DB']->exec_SELECTcountRows('uid', 'sys_workspace', $where);
+			$oldStyleWorkspaceIsUsed = $count > 0;
+			$GLOBALS['BE_USER']->setAndSaveSessionData($cacheKey, !$oldStyleWorkspaceIsUsed);
+		} else {
+			$oldStyleWorkspaceIsUsed = !$cacheResult;
+		}
+		return $oldStyleWorkspaceIsUsed;
+	}
 }
 
 
Index: Classes/ViewHelpers/TempFlashMessageQueueViewHelper.php
===================================================================
--- Classes/ViewHelpers/TempFlashMessageQueueViewHelper.php	(revision 0)
+++ Classes/ViewHelpers/TempFlashMessageQueueViewHelper.php	(revision 0)
@@ -0,0 +1,65 @@
+<?php
+/*                                                                        *
+ * This script belongs to the FLOW3 package "Fluid".                      *
+ *                                                                        *
+ * It is free software; you can redistribute it and/or modify it under    *
+ * the terms of the GNU Lesser General Public License as published by the *
+ * Free Software Foundation, either version 3 of the License, or (at your *
+ * option) any later version.                                             *
+ *                                                                        *
+ * This script is distributed in the hope that it will be useful, but     *
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN-    *
+ * TABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser       *
+ * General Public License for more details.                               *
+ *                                                                        *
+ * You should have received a copy of the GNU Lesser General Public       *
+ * License along with the script.                                         *
+ * If not, see http://www.gnu.org/licenses/lgpl.html                      *
+ *                                                                        *
+ * The TYPO3 project - inspiring people to share!                         *
+ *                                                                        */
+
+/**
+ * View helper which renders the FlashMessageQueu
+ *
+ * = Examples =
+ *
+ * <code title="Minimal">
+ * <f:be.flashMessageQueue />
+ * </code>
+ *
+ * Output:
+ * All FlashMessages which were registered using t3lib_FlashMessageQueue::addMessage($message);
+ *
+ * @author      Tolleiv Nietsch <info@tolleiv.de>
+ * @license     http://www.gnu.org/copyleft/gpl.html
+ * @version     SVN: $Id:
+ *
+ */
+
+/**
+ * ViewHelper to integrate the backend FlashMessageQueue into our module
+ *
+ * @todo Remove this viewHelper once http://forge.typo3.org/issues/10821 is available
+ */
+class Tx_Workspaces_ViewHelpers_TempFlashMessageQueueViewHelper extends Tx_Fluid_ViewHelpers_Be_AbstractBackendViewHelper {
+
+
+	/**
+	 * Renders a shortcut button as known from the TYPO3 backend
+	 *
+	 * @return string the rendered flashMessage
+	 * @see template::makeShortcutIcon()
+	 */
+	public function render() {
+
+		$renderedMessages = '';
+		$flashMessages = t3lib_FlashMessageQueue::renderFlashMessages();
+		if (!empty($flashMessages)) {
+			$renderedMessages = '<div id="typo3-messages">' . $flashMessages . '</div>';
+		}
+
+		return $renderedMessages;
+	}
+}
+?>
\ No newline at end of file
Index: Resources/Private/Language/locallang.xml
===================================================================
--- Resources/Private/Language/locallang.xml	(revision 2842)
+++ Resources/Private/Language/locallang.xml	(working copy)
@@ -67,6 +67,7 @@
 			<label index="window.sendToNextStageWindow.additionalRecipients">Additional recipients</label>
 			<label index="window.sendToNextStageWindow.comments">Comments</label>
 			<label index="error.getStageTitle.stageNotFound">Stage not found</label>
+			<label index="warning.oldStyleWorkspaceInUser">It seems that you're stil using old-style workspace. If you continue using this module without migrating your workspace you might loose data.</label>
 		</languageKey>
 	</data>
 </T3locallang>
\ No newline at end of file
Index: Resources/Private/Layouts/module.html
===================================================================
--- Resources/Private/Layouts/module.html	(revision 2842)
+++ Resources/Private/Layouts/module.html	(working copy)
@@ -1,3 +1,4 @@
+{namespace this=Tx_Workspaces_ViewHelpers}
 <!-- ###FULLDOC### begin -->
 <div class="typo3-fullDoc">
 <!-- Page header with buttons, path details and csh -->
@@ -18,6 +19,9 @@
 <!-- Content of module, for instance listing, info or editing -->
 <div id="typo3-docbody">
 <div id="typo3-inner-docbody">
+
+	<this:TempFlashMessageQueue />
+
 	<f:render partial="navigation" arguments="{workspaceList: workspaceList, activeWorkspaceUid: activeWorkspaceUid, showAllWorkspaceTab:showAllWorkspaceTab}" />
 	<div class="typo3-dyntabmenu-divs"><f:render section="main" /></div>
 	<f:if condition="{showLegend}"><f:render partial="legend" /></f:if>
