Index: wp-includes/cron.php
===================================================================
--- wp-includes/cron.php	(revision 19681)
+++ wp-includes/cron.php	(working copy)
@@ -164,6 +164,28 @@
 		wp_unschedule_event( $timestamp, $hook, $args );
 }
 
+/** 
+* Unschedule all previously scheduled cron job for a hook. 
+*
+* Can be usefull for plugins when deactivating to clean up the cron queue 
+* 
+* The $hook parameter is required, so that the events can be 
+* identified. 
+* 
+* @since 3.4 
+* 
+* @param string $hook Action hook, the execution of which will be unscheduled. 
+*/ 
+function wp_unschedule_hook( $hook ) { 
+	$crons = _get_cron_array(); 
+	foreach( $crons as $timestamp => $args ) { 
+		unset( $crons[$timestamp][$hook] ); 
+		if ( empty( $crons[$timestamp] ) )
+			unset( $crons[$timestamp] ); 
+	} 
+	_set_cron_array( $crons ); 
+} 
+
 /**
  * Retrieve the next timestamp for a cron event.
  *