For those who are running small servers and wish to accelerate their worpdress installation, we recommend the installation of eaccelerator but also the wp-super-cache plugin. There is just a small hack for wordpress 3.0 menu users : the cache should be totally refreshed when a menu is modified, and this is performed via the wp_update_nav_menu action, instantiated in the wp-cache-phase2.php / wp_cache_phase2 function
add_action("wp_update_nav_menu" , 'wp_cache_clear_cache' );
cache clear for POD CMS
Generally, all actions that update content from the admin should clear the cache. the following line, to be added in the same manner, will catch the pod cms update action and clear the cache (pod cms forum discussion).
Same job for other plugins : look for a hook (search do_action in files) and use the save action of your plugin data to clear the cache .