The Barebones SSO Server/Client software that this plugin integrates with is located at:
http://barebonescms.com/documentation/sso/
This plugin completely overrides the MyBB login system infrastructure with centralized user account management (the SSO server). This plugin takes care to preserve existing user accounts via the user's e-mail address. If a user signs in with the same e-mail address as their existing MyBB account, the accounts will be seamlessly and transparently linked together.
Due to the intricacies of overriding the MyBB login system, this is a slightly fragile plugin and may break whenever MyBB or the SSO client are upgraded. This is generally the case whenever two very large systems are brought together. The plugin here on MyBB mods may lag behind the latest version. The latest versions of MyBB, this plugin, and the SSO client will usually work together without any issues.
Questions and comments about this plugin should be directed here:
http://barebonescms.com/forums/