First problem that comes to mind is people spamming inappropriate edits.

Need a way to weigh reputation that can't be gamed.

Maybe look at the size of their social graph 3 degrees of separation out. Followers is to easy to fake. But if your followers have to have followers, etc, that's harder to fake.

If somebody has a large following of real human users then that is an indication that the community values what this user has to say. So their wiki edits should be given more weight.