Possible to use conditional shortcodes in templates?

I'm trying to do something like:
<? echo do_shortcode('[am4guest]'); ?>
<a href="<? bloginfo('url'); ?>/members/login">Login</a>
<? echo do_shortcode('[/am4guest]'); ?>

..in my header.php file, but the ending shortcode just returns /am4guest instead of actually closing the conditional.

Anyone have any solutions for running conditional shortcodes like this in templates?

I figured out that you can concatenate shortcodes like so:
<? echo do_shortcode(
'[am4guest]' .
'<li class="first"><a href="' . get_bloginfo('url') . '/members/login">Login</a></li>
<li><a href="' . get_bloginfo('url') . '/signup">Become a Member</a></li>' .
'[/am4guest]');
?>

Nice hack!

Thanks for sharing.

David