TechCrunch wrote a great article about the backlash against negative reviews on Yelp.
I totally drink the kool-aid when it comes to Yelp, and I think it's one of the coolest things on the Internet right now. I yelp about every place I go. I use it every time I travel. I want a Windows Mobile Yelp Client for Xmas.
There was a comment to the TechCrunch article that said that the "concern is that competitors and not customers are posting poor reviews." The idea that business owners are going around making bad Yelp posts about their competitors seems a little far fetched to me, given that I personally have never come across a place that didn't deserve their rating, but even if this was true, wouldn't it just be canceled out with the glowing endorsement the competitor business owner gave his own page? On the whole, this dance routine just doesn't happen.
But the greatest thing of all about this story is every new website created to slander Yelp merely gets the word out further. Yelp.com, like many things on the Internet, only works with high visibility and user input. Every time the site is mentioned, it adds credibility. I think this double-edge sword is an interesting phenomena. People who do not like the site are left with little recourse, except to hope it's a fad that blows over... or it gets harvested by Google.