=== modified file 'uc_cart/uc_cart.module'
--- uc_cart/uc_cart.module	2009-10-20 20:42:37 +0000
+++ uc_cart/uc_cart.module	2009-11-02 19:06:16 +0000
@@ -1674,12 +1674,18 @@
     return FALSE;
   }
 
+  $result = array();
+
   // See if any other modules have a say in the matter...
   foreach (module_list() as $module) {
     $func = $module .'_cart_item';
-    if (function_exists($func) && $func('can_ship', $product)) {
+    if (function_exists($func)) {
       // $product must be passed by reference.
-      $result[] = TRUE;
+      $return = $func('can_ship', $product);
+
+      if (!is_null($return)) {
+        $result[] = $return;
+      }
     }
   }