/**
 * Disable Update Notifications
 *
 * 
 */
function disable_update_notifications()
{
    global $wp_version;
    return (object) array(
      'last_checked'=> time(),
      'version_checked'=> $wp_version
    );
}
add_filter('pre_site_transient_update_core','disable_update_notifications');
add_filter('pre_site_transient_update_plugins','disable_update_notifications');
add_filter('pre_site_transient_update_themes','disable_update_notifications');