Depends on what you mean by "supported"... If you're looking at using jForum's login screens and having it authenticated against LDAP with a minimum of information copied to the jForum user DB, there is an LDAPAuthenticator class that can be used.
If you're looking for a complete SSO situation, there is a simple way that works with a lot of web app servers. That is to do the following:
Use their LDAP SSO security implimentation (E.g.
Tomcat's LDAP realm implimentation).
Secure the jForum web-app using standard web.xml security constriants.
Then configure jForum to use the RemoteUserSSO class.
This has some issues like not allowing anonymous access and not passing detailed LDAP info into jForum.
If you need something more complex, it's not that hard to write your own LDAP SSO implimentation.
[originally posted on jforum.net by monroe]