I received numerous questions about using the authentication plugin. The top question was: "does it work in Joomla 1.0?". I'm afraid it doesn't and it probably never will. If your keen on knowing how to use the plugin and don't know where to start: please watch this video (and ignore the wobbly english).
I wrote a plugin for Joomla 1.5 and SugarCRM (4.5 or higher) that authenticates SugarCRM contacts in Joomla. If you install this plugin you can automatically grant your clients access to your public website, without actually giving them an account in the website software. The plugin is based on the new modular authentication system in Joomla 1.5. An administrator configures which fields in the SugarCRM contacts module are used as username and password.