It seems that internal ls feature has been disabled (because it's "experimental") in RC1 wu-ftpd. This makes the life _very_ difficult for people who use guest accounts, ie. chroot all users to their own homedirs. This is one of the integral features of wu-ftpd. Are there any real issues supporting disabling internal ls? It's not like Red Hat Linux doesn't have any other experimental features in anyway ;)
If you need it, recompile. We don't want to be responsible for servers crashing because of possible memory leaks and other bugs...