WordPress MU

how can i get the IP address for new user blogs?

Here's an mu-plugin:

function get_blog_registration_ip () {
	global $wpdb;
	global $blog;
		$ip = $wpdb->get_var( "SELECT IP FROM {$wpdb->registration_log} WHERE blog_id = ".$blog[ 'blog_id' ]."" );
?>
IP: <strong><?php echo $ip; ?></strong>
<?php
}
add_action('wpmublogsaction', 'get_blog_registration_ip' );
?>