Carl and Richard talk to Jeff Wilcox about his work on 4th and Mayor. 4th and Mayor is a third-party Foursquare app currently only available for Windows Phone 7. Jeff discusses how he got into building the app initially and how it has become one of his favorite 'hobbies'. The conversation explores some of the challenges of building the application, dealing with shifting APIs and publication delays in the marketplace and how node.js helps on the backend for providing notifications and updates.