Changes since 6.x-1.3:
* Followup fix to styles CSS since the Colorbox plugin removed the hover class in favor of CSS hover state some time back.
* Drush command now automatically renames the "colorbox-1.3.18" directory to "colorbox".
* Back-ported the Drush command improvements from Drupal 7 version.
If no major bugs show up this is quite likely the last release for Drupal 6.