I've been researching a way to get SSO for my school, and there are some good reasons why I'd like our Moodle installation to be the source for usernames and passwords. Basically, all of our support staff are trained in moodle, know how to log in as someone else, change their password for them, etc.
I have also set up an email server that is just an ubuntu box and now I'd like users to use the same username and password as our Moodle whenever they log in to those ubuntu accounts (via imap or pop, which is already set up).
Obviously, the way to do this is to use a PAM module that connects to the web services API. I've done some cursory searches and haven't found anything useful, but I can't see how it would be too hard.
I'm not able to write the PAM module myself, but I could modify one that's already in the wild. Seems to me something useful to have in some cases.