http://www.yelp.com/static?country_=US&p=tos> You alone are responsible for Your Content, and once published, it cannot always be withdrawn.
> We may use Your Content in a number of different ways, including publicly displaying it, reformatting it, incorporating it into advertisements and other works, creating derivative works from it, promoting it, distributing it, and allowing others to do the same in connection with their own websites and media platforms ("Other Media"). As such, you hereby irrevocably grant us world-wide, perpetual, non-exclusive, royalty-free, assignable, sublicensable, transferable rights to use Your Content for any purpose. Please note that you also irrevocably grant the users of the Site and any Other Media the right to access Your Content in connection with their use of the Site and any Other Media. Finally, you irrevocably waive, and cause to be waived, against Yelp and its users any claims and assertions of moral rights or attribution with respect to Your Content. By "use" we mean use, copy, publicly perform and display, reproduce, distribute, modify, translate, remove, analyze, commercialize, and prepare derivative works of Your Content.
They follow that with
> As between you and Yelp, you own Your Content. We own the Yelp Content, including but not limited to visual interfaces, interactive features, graphics, design, compilation, including, but not limited to, our compilation of User Content and other Site Content, computer code, products, software, aggregate user review ratings, and all other elements and components of the Site excluding Your Content, User Content and Third Party Content. We also own the copyrights, trademarks, service marks, trade names, and other intellectual and proprietary rights throughout the world ("IP Rights") associated with the Yelp Content and the Site, which are protected by copyright, trade dress, patent, trademark laws and all other applicable intellectual and proprietary rights and laws. As such, you may not modify, reproduce, distribute, create derivative works or adaptations of, publicly display or in any way exploit any of the Yelp Content in whole or in part except as expressly authorized by us. Except as expressly and unambiguously provided herein, we do not grant you any express or implied rights, and all rights in and to the Site and the Yelp Content are retained by us.
Which is, I think, an effort to distance themselves if someone posts "I totally saw the chef drop the steak on a dirty floor and put it on a plate" type lies.