I've been tinkering with the latest iPhone app from Yelp! but the experience has been somewhat lacking when compared to Foursquare. First is that Yelp focuses on places to eat rather than on the true GPS coordinates of the user. So when you show up at anything other than a restaurant you have to search for the business. Another thing is when a business that should be listed isn't there isn't really a quick and easy way to add one, if at all, in the application. But really, there isn't much motivation to add anything or become a frequent visitor anyway other than bragging rights? The fun with Foursquare and Gowalla is that there is a competition between users to become the mayor. The check in process feels like a forced feature to compete with location based services but they haven't quite figured it out.