Yahoo! recently embraced OpenID . It seems OpenID will be a de-facto SSO building block.

If UBBThreads provides an OpenID provider (server) feature , admin can build other applications regardless of UBBThreads's data structure (db schema , cookie authentication , md5 hashing ...etc), just sees UBBThreads' user as an authenticated OpenID user , let UBBThreads authenticate the user.

I think it will be very great. I don't need to maintain my Java-to-UBBThreads OR-mapping code.

Reference :

OpenID Bootcamp Tutorial , the most famous document.
http://www.slideshare.net/daveman692/openid-bootcamp-tutorial/

phpMyID : a standalone, single user, OpenID Identity Provider.
http://siege.org/projects/phpMyID/
I think UBBThreads can refer to its code to implement a OpenID server.

English is not my native language. I try my best to express my thought precisely. I hope you understand what I mean. If any misunderstanding results from culture gaps, I apologize first.