Add a new cache class, MMAccessCacheMemcache, which can be used to improve performance on systems using the memcache module. To enable, add this line to your settings.php file, alongside other memcache configurations: $conf['cache_class_mm_access_cache'] = 'MMAccessCacheMemcache';
Automatically flag the "All logged-in users" virtual group to be updated during the next cron run whenever a user is added or removed. Courtesy of Hilary C.