Sorry for the slow reply Chris, and Hi Zane.
I was using this on the homepage of a site, which required the user to be logged in to visit a lot of the links on the homepage. So I created a page template which outputted different classes depending if the user was logged in or not. I only targeted the logged out class with this plugin.
I was under immense time pressure from a client to get this fixed, so what I'd implemented was terribly messy, and definitely not something I recommend!! Though it does work.
I'm going to be busy for the next month so I wont be able to submit a patch for this, but I do think this plugin is great, though could be fleshed out even more! For instance if it could allow the site owner to mark a post as private, and then require a user to register/login. Would this be out of the scope you'd planned for your plugin?