Well, now that I have the admin GUI even running at all, it seems that I can change existing users but I can't create new ones with it.
When I fill out the form and hit "save" I get the following:
I also get the following in syslog:
Error code: com.openexchange.admin.plugins.PluginException: com.openexchange.admin.rmi.exceptions.OXUserIMAPException: unable to create INBOX (SVL-0001,-71434159-164)
Which seems odd, since its saying I can't create the inbox, but yet it logs in as the new user.
Feb 27 16:51:15 elise imap: login: localhost [127.0.0.1] jbritton PLAIN User logged in
I was able to work around the problem by going into cyradm and creating the mailbox "user/jbritton" from cyradm first, and then the admin GUI allowed me to add the user.
Strange -- why can't the admin GUI do what cyradm does? It's got the authentication information I used to log into the admin GUI itself, which is all it should need.