Yesterday I gave my Inheritance versus Roles talk. The slides aren't really enough to follow along, but I've also uploaded a PDF of an extended version of the talk. Both are available under the GNU free documentation license and both can be downloaded (see the "Get File" link at the top of each).
Next time I give this talk, I think I should rewrite parts of it. The B:: hierarchy section was a bit too abstract for people. I think I can omit that and include more role examples to let people really appreciate the power of what they're getting.