This has come up before. I would be interested in helping, and think I can point you to a few others who might be as well.

This thread: 324924 contains some discussion. We wondered whether the best way to teach newbies is through a wiki, a parallel XP system for completing Perl challenges, or an RPG... Any of those might be fun to work on, or use.

I thought this thread was also related, but perhaps because I'm very interested in the subject: 325375

I suppose the only two really useful approaches would either be something simple that would very intelligently evolve, or something very well planned out that could be useful without a huge amount of content. (It seems the two biggest drawbacks would be not enough content, or not finding a working/popular teaching approach. (I presume teaching people who are not forced to learn; as you're the professor, you may not need to worry.)