I've been kicking around a similar idea, but with a stronger emphasis on the user model as a mentor/apprentice experience. It would be certainly harder to implement than what you are describing, which, and correct me if I'm way off here, would be a set of interactive lesson plans presented in a fashion similar to a wiki where the end-user gains experience and credibility given their progression and rank (or karma, points accumulated) for a set of lessons belonging to a particular category or domain of interest. As they gain more credibility for domain they are granted additional permissions for editing or adding content for that domain.
