I was trying to get your plugin to work with featured images from a NextGEN gallery... You have to use "get_the_post_thumbnail($post->ID, "post-thumbnail");" but it still wasn't working for me... Then I found the following info:
"If the required add_theme_support( 'post-thumbnails' ); in the current theme's functions.php file is attached to a hook, it must be must be called before the init hook is fired. The init hook may be too late for some features. If attached to a hook, it must be after_setup_theme."
I'm a perl guy, trying to do my best in php... Is there anything I can change in my theme's function.php file to make get_the_post_thumbnail work in your plugin?