Remove check for 'Anyone can register' setting in url slugs.  It's entirely possible that users would be created or generated outside the UI, or at a time where it was possible for users to register.
Standardize on WP eCommerce
Ensure that shortcodes pages, which are for the 1.0 theme engine, are only created for the 1.0 theme engine.
Don't show checkout steps on transaction results page.
Conflict merge