Index: typo3/sysext/install/mod/class.tx_install.php
===================================================================
--- typo3/sysext/install/mod/class.tx_install.php	(revision 7609)
+++ typo3/sysext/install/mod/class.tx_install.php	(working copy)
@@ -225,7 +225,8 @@
 		'cleanup' => 'Clean up',
 		'phpinfo' => 'phpinfo()',
 		'typo3conf_edit' => 'Edit files in typo3conf/',
-		'about' => 'About'
+		'about' => 'About',
+		'logout' => 'Logout from Install Tool',
 	);
 	var $JSmessage = '';
 
@@ -271,7 +272,7 @@
 		if ($_GET['TYPO3_INSTALL']['type']) {
 			$allowedTypes = array(
 				'config', 'database', 'update', 'images', 'extConfig',
-				'cleanup', 'phpinfo', 'typo3conf_edit', 'about'
+				'cleanup', 'phpinfo', 'typo3conf_edit', 'about', 'logout'
 			);
 
 			if (in_array($_GET['TYPO3_INSTALL']['type'], $allowedTypes)) {
@@ -535,7 +536,7 @@
 		if ($this->step) {
 			$this->output($this->outputWrapper($this->stepOutput()));
 		} else {
-			
+
 				// Menu...
 			switch($this->INSTALL['type']) {
 				case 'images':
@@ -728,6 +729,14 @@
 					$this->silent=0;
 					$this->typo3conf_edit();
 				break;
+				case 'logout':
+					$enableInstallToolFile = PATH_site . 'typo3conf/ENABLE_INSTALL_TOOL';
+					if (is_file($enableInstallToolFile) && trim(file_get_contents($enableInstallToolFile)) !== 'KEEP_FILE') {
+						unlink(PATH_typo3conf . 'ENABLE_INSTALL_TOOL');
+					}
+					$this->session->destroySession();
+					t3lib_utility_Http::redirect($this->scriptSelf);
+				break;
 				case 'about':
 				default:
 					$this->silent=0;
@@ -7578,7 +7587,7 @@
 			t3lib_div::createVersionNumberedFilename(
 				'../contrib/prototype/prototype.js'
 			) . '"></script>';
-			
+
 			// Add JS functions for output
 		$this->javascript[] = '<script type="text/javascript" src="' .
 			t3lib_div::createVersionNumberedFilename(
@@ -7626,7 +7635,7 @@
 				t3lib_div::createVersionNumberedFilename($this->backPath .
 					'sysext/install/Resources/Public/Stylesheets/install.css'
 				) . '" />';
-		} else {			
+		} else {
 				$this->stylesheets[] = '<link rel="stylesheet" type="text/css" href="' .
 					t3lib_div::createVersionNumberedFilename($this->backPath .
 					'sysext/install/Resources/Public/Stylesheets/install.css'
Index: typo3/sysext/install/mod/class.tx_install_session.php
===================================================================
--- typo3/sysext/install/mod/class.tx_install_session.php	(revision 7609)
+++ typo3/sysext/install/mod/class.tx_install_session.php	(working copy)
@@ -148,6 +148,14 @@
 	}
 
 	/**
+	 * Destroys a session
+	 *
+	 */
+	public function destroySession() {
+		session_destroy();
+	}
+
+	/**
 	 * Generates a new session ID and sends it to the client.
 	 *
 	 * Also moves session information from the old session to the new one
Index: typo3/sysext/install/Resources/Public/Stylesheets/general.css
===================================================================
--- typo3/sysext/install/Resources/Public/Stylesheets/general.css	(revision 7609)
+++ typo3/sysext/install/Resources/Public/Stylesheets/general.css	(working copy)
@@ -268,6 +268,10 @@
 	background-image: url('../Images/menuAbout.png');
 }
 
+#t3-install-menu #t3-install-menu-logout {
+	background-image: url('../Images/login-icon-key.gif');
+}
+
 #t3-install-links {
 	margin: 2em 0 0 0.8em;
 	padding: 0;