gistfile1.txt

<?php
/*
Plugin Name: Gist Watermark
Plugin URI: http://clifgriffin.com
Description:  Nothing really.
Version: 1.0
Author: Clifton H. Griffin II
Author URI: http://clifgriffin.com
*/

class GistTest {
  function __construct() {
		// Cover image was the most to convenient to test with in my install
		add_action( 'shopp_themeapi_product_coverimage', array($this, 'destroy_images_array'), 1, 3);
		add_action( 'shopp_themeapi_product_coverimage', array($this, 'didnt_work'), 100, 3);
	}

	function destroy_images_array($result, $options, $O) {
		$O->images = null;
		return $result;
	}

	function didnt_work($result, $options, $O) {
		print_r($O->images); // this shouldn't show anything, right?
		return $result;
	}
}

$GistTest = new GistTest();