Eric Meyer talks about teaching without qualifications, though still having the skillset:
Allow a History major to teach in a computer science department at a University? [...] am I not qualified to teach students how to assemble a Web design, and about the underpinnings of today's Web, with an eye to the future? I certainly think I am, at least from a skills point of view; whether or not I'd make a good teacher of people is another question entirely, of course. The deepest experts can be the worst teachers, something all of us probably encountered at some point in our eductional experiences.
Something I've been thinking about lately, with my political science degree but interest in web design and such. This as I consider doing the social studies stream of PDP.