I've posted a few reviews on Yelp myself - I'm definitely not one of the elite, but I will say, the time I got double charged on my credit card, and a week later the restaurant was closed, when I yelped about it, I got some attention. That restaurant owner got on the phone and refunded my over charge asap. Yelp definitely holds some clout.
The Online Reviewing Mafia
The Online Reviewing Mafia
Etc. Food Crazies, June6 - June 12, 2011 edition of Bloomberg Businessweek