Well I got my feed published last night, but the image tags aren't being output. Someone in irc said it might be this code:

433 if (variable_get("rss_item_picture",'0') == 1) {
434 if (isset($product->field_image_cache) && file_exists($product->fiel d_image_cache[0]['filepath'])){
435 $output .= "<".$gg."image_link>" . $GLOBALS['base_url'] .'/'. ($product ->field_image_cache[0]['filepath']) . "\n";
436 }
437 }

I was told to try changing it to this:

436 if (variable_get("rss_item_picture",'0') == 1) {
437 if (isset($product->field_image_cache) && file_exists('./' . $produc t->field_image_cache[0]['filepath'])){
438 $output .= "<".$gg."image_link>" . $GLOBALS['base_url'] .'/'. ($product ->field_image_cache[0]['filepath']) . "\n";
439 }
440 }

which didn't work.

Here's another link that may explain the issue: http://www.php.net/manual/en/function.file-exists.php#93572

I'm new to Drupal development, so I'm not surprised that I couldn't get it. Maybe someone else has a better idea.