It looks like I’m not the first one to think of assigning students to edit Wikipedia articles (not that I actually thought I was). T. Mills Kelly at George Mason University reports on his experiments with using Wikipedia assignments (and his experience of receiving papers bases primarily on Wikipedia sources). However, Kelly researches “the influence of digital media on student learning in history,” so (ironically) it’s not just being used for pedagogical purposes in this case.
I’m not sure how much say I’ll have when I’m a TA next year, but I’m going to start my Wikipedia assignments then if I can get away with it.