network_admin_notices action-hook . WP 3.1.0

Prints network admin screen notices.

add_action( 'network_admin_notices', 'action_function_name_2473' );
function action_function_name_2473(){
	// action...
}

In file: /wp-admin/admin-header.php

network_admin_notices

do_action( 'network_admin_notices' );

add_action( 'network_admin_notices', 'new_user_email_admin_notice' );

add_action( 'network_admin_notices', 'site_admin_notice' );

add_action( 'network_admin_notices', 'update_nag', 3 );

add_action( 'network_admin_notices', 'maintenance_nag', 10 );