get custom field within an array?

Hi

I need to display a different URL on a page depending on the value query string in the URL. I’ve set up an array but I want the value returned to be the value of a custom field in a post. so ?id=s returns the custom field value of ‘iphone_app_link_sms’

This is my code but it just returns ‘array’. Can someone please help and suggest a solution?

Many thanks

global $iosurl;
$iosurl = array(
'e' => get_post_meta($post->ID, 'iphone_app_link', true),
's' => get_post_meta($post->ID, 'iphone_app_link_sms', true)
);
if(array_key_exists($_GET['id'], $iosurl))
      {

	   echo $iosurl[$_GET['id']]; exit;
	  }