Index: colorbox.drush.inc
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/colorbox/drush/colorbox.drush.inc,v
retrieving revision 1.3
diff -u -p -r1.3 colorbox.drush.inc
--- colorbox.drush.inc	18 Apr 2010 16:47:08 -0000	1.3
+++ colorbox.drush.inc	16 May 2010 07:01:32 -0000
@@ -72,6 +72,10 @@ function colorbox_drush_help($section) {
  *
  */
 function drush_colorbox_plugin() {
+  if (!drush_shell_exec('type -P unzip')) {
+    return drush_set_error(dt('Missing dependency: unzip. Install it before using this command.'));
+  }
+
   $args = func_get_args();
   if ($args[0]) {
     $path = $args[0];