Index: typo3/sysext/cms/tslib/class.tslib_fe.php
===================================================================
--- typo3/sysext/cms/tslib/class.tslib_fe.php	(revision 4494)
+++ typo3/sysext/cms/tslib/class.tslib_fe.php	(working copy)
@@ -1792,8 +1792,22 @@
 	function cHashParams($addQueryParams) {
 		return t3lib_div::cHashParams($addQueryParams);
 	}
-
+	
 	/**
+	 * Sets the cache expiration timestamp
+	 * 
+	 * @param	integer		Expiration timestamp when the cache is outdated
+	 * @return	void
+	 * @access public
+	 */	
+	function setPageCacheExpiresTimestamp($timestamp) {
+		if ($timestamp > $GLOBALS['EXEC_TIME'] && ($this->cacheExpires == 0 || $timestamp < $this->cacheExpires)) {
+			$this->cacheExpires = $timestamp;
+		}
+	}
+	
+	
+	/**
 	 * Initialize the TypoScript template parser
 	 *
 	 * @return	void
@@ -2694,6 +2708,16 @@
 	function setPageCacheContent($content, $data, $expirationTstamp) {
 		$this->clearPageCacheContent();
 
+			// only if content is not "message_page_is_being_generated"
+			// which expires after 30 seconds
+		if (!$this->tempContent) {
+				// can be changed from an extension via $GLOBALS['TSFE']->setPageCacheExpiresTimestamp()
+				// $this->cacheExpires is default 0
+			if ($this->cacheExpires > $GLOBALS['EXEC_TIME'] && $expirationTstamp > $this->cacheExpires) {
+				$expirationTstamp = $this->cacheExpires; 
+			}
+		}		
+		
 		$cacheData = array(
 			'hash'         => $this->newHash,
 			'page_id'      => $this->id,