I'm thinking about the my Roles talk at YAPC::EU::2009, (you know the conference, right? The one I made that strange little promo for?). It's a bit of a tutorial, but not much. It's more about the "why" instead of the "how" because even though I get plenty of comments/emails about roles, they're almost always in the "why" category. That's because roles are so easy to use once you start that you really need motivation for starting rather than a guide on how to start (though I'll give some of that, too).