Part of the point of the review model of Yelp (and Amazon, for that matter) is that you don't have to trust a review. You only have to trust the consensus of all of the reviewers - which, at best, is very, very hard to spoof. When I see a place on yelp with a 4-star average on 1000 reviews, I feel very confident about going there. It's hard to get to that critical mass, but far from impossible - and you don't need someone's "real name." This is actually somewhere where Yelp is doing well, too - they give people a _persistent_ identity. You should trust reviews from someone who's written 100 reviews more than a review from someone who signed up just to review a single place - and Yelp makes that judgment easy by putting the information right in front of you. Blizzard and other strategies have demonstrated that real names aren't necessary for a good community - just persistent names.

Also, I have to laugh that the UrbanTag folks approvingly cite the complaint that existing reviews sites are "giving customers “the upper hand” in determining an establishment’s reputation." Well, yes, they are. That's the point. That power has always rested in customers' hands, because that's what reputation is: what other people think of you. You can work on your reputation and "manage" it and "optimize" it, but if it's not what other people think, it's not reputation. Business owners neither need nor deserve control over other people's opinions - look at those asshole doctors that were linked here a while back, forcing customers to sign agreements that amounted to "we can sue you for posting a negative review of us on Yelp."

As for unreasonable customers: that's nearly as overblown as the threat of piracy, and if your business can't deal with unreasonable customers gracefully (not the same as caving and giving them what they ask for), you deserve to go out of business.