I have the custom meta box showing when I add and/or edit a post. The "Product Information" option shows up in the Screen Options tab.
On page 147 the first paragraph states "You can easily display your saved meta box data in your theme using the get_post_meta function inside the Loop like so:"
I am using WordPress 3.0.1 with the Twenty Ten theme. I assume you mean the wp-content\themes\twentyten\loop.php file. After studying the code I have placed the recommended code in a couple of places with no luck.
I am sure it will be obvious once I read chapter 8 Theme Development, but I was hoping for a little more help at this point.