Which WordPress tempalte are you currently one? http://wp.me/p4gJ2a-Be

ap-show-template.php

function ap_show_template() {

	// bail early
	if ( is_admin() || !is_user_logged_in() )
		return;
	
	if ( !is_admin_bar_showing() || !current_user_can( 'edit_files' ) )
		return;
		
	global $template, $wp_admin_bar;
	
	$title = ( isset( $template ) ) ? str_replace( array( get_template_directory(), get_stylesheet_directory() ), '', $template ) : 'Unknown';
		
	$wp_admin_bar->add_node( array(
		'parent'	=> false,
		'id'		=> 'template',
		'title'		=> $title,
		'href'		=> '#'
	) );
	
	// optional add number queries under the template
	$wp_admin_bar->add_node( array(
		'parent'	=> 'template',
		'id'		=> 'queries',
		'title'		=> sprintf( esc_attr( '%s queries in %s sec' ), get_num_queries(), timer_stop() ),
		'href'		=> '#'
	) );

}
add_action( 'admin_bar_menu', 'ap_show_template', 10 );

quicker way to check admin perms?

if ( ! current_user_can( 'manage_options' ) ) {
    return false;
}

Updated the code.