Just read a very good article by Duncan Parry of Pay Per Click Analyst called Social Networks, Customer Reviews and Local Search: Rude Waiters Beware the Search Engines.
The gist of it is that there are increasingly more opportunities on the Internet through community forums, blogs and other websites for customers to post their comments and reviews about businesses. This is particularly directed at local search directories where people can get reviews of local businesses.
So what does that mean for the business owner? Put simply: run your business well, provide a good service and you should have nothing to worry about. In fact as local search and business reviews become more widely used and spread to mobile phones you may find local search increasing sales (although this won´t be noticeable for some time if it does happen — local search is still in it´s infancy).