Here are some screen shots from my Joomdle test server. I am running Joomla 1.7 and Moodle 2.1.2. In our environment we use LDAP for logins. I am not sure I have the users synced and single sign on working completely. No errors, but I am not sure users in Moodle are imported into Joomla properly. Still Working on that.
Below are the screenshots: