I think, that bad thing to allow all contributor's able to see IPs of all comments.
So, i have changed wp-admin/includes/template.php in this way:
replaced
<?php _e('IP:') ?> <a href="http://ws.arin.net/cgi-bin/whois.pl?queryinput=<?php comment_author_IP() ?>"><?php comment_author_IP() ?></a>
in _wp_comment_list_item with
<?php if ( current_user_can( 'moderate_comments' ) ) { ?>
<?php _e('IP:') ?> <a href="http://ws.arin.net/cgi-bin/whois.pl?queryinput=<?php comment_author_IP() ?>"><?php comment_author_IP() ?></a>
<?php } ?>
and in _wp_get_comment_list changed SQL from
$comments = $wpdb->get_results("SELECT SQL_CALC_FOUND_ROWS * FROM $wpdb->comments WHERE
(comment_author LIKE '%$s%' OR
comment_author_email LIKE '%$s%' OR
comment_author_url LIKE ('%$s%') OR
comment_author_IP LIKE ('%$s%') OR
comment_content LIKE ('%$s%') ) AND
comment_approved != 'spam'
ORDER BY comment_date DESC LIMIT $start, $num");
to
$comments = $wpdb->get_results("SELECT SQL_CALC_FOUND_ROWS * FROM $wpdb->comments WHERE
(comment_author LIKE '%$s%' OR
comment_author_email LIKE '%$s%' OR
comment_author_url LIKE ('%$s%') OR
".(current_user_can( 'moderate_comments' ) ? " comment_author_IP LIKE ('%$s%') OR " : "")."
comment_content LIKE ('%$s%') ) AND
comment_approved != 'spam'
ORDER BY comment_date DESC LIMIT $start, $num");