you will want to take a look at how wikileaks does it thing. you will need people in asset havens like bahamas/etc uploading you stuff on the sly, as my understanding is a lot of the way this works is simply information hiding by having an official registry that is text only, having legal standing, not searchable in any electronic way. when a crime is committed you get to initiate a legal proceeding that will eventually unravel the paper trail in the bahamas or wherever, but each step takes n amount of time, and when you have shell companies under shell companies the stalling strategy can be quite effective.
It's going to be quite difficult. I am also concerned about the legal issues I may face. I don't doubt we'll get C&D's and other legal threats for defamation or libel.
I really don't know what I'm getting myself into here, but I feel drawn to it.
I'm not a yelp user, but the other problem that occurs to me is the anonymity.
Of course you have user profiles, but you can't (easily) track a review back to a human being, which is why this was such a shock to the reviewer in the magazine article when it actually happened.
The businesses stand there naked and the reviewers can take little potshots at them behind the screen of anonymity. No wonder some people go a little crazy.
If yelp made reviewers less anonymous, such as stating where you work, maybe this would be less of a problem.
At least bad reviews would probably be polite and dignified rather than outright nasty.
Forever.