The rapid development of wireless technology, the extensive use of mobile phones and the availability of location information are facilitating personalized location-based applications. Easy to carry, easy to use and easy to buy, smart phones with certain software are of great advantage. Consequently, mobile social networking (MSN) systems have emerged rapidly, being a revolution for our everyday life. Based on the analysis of general requirements of MSN and location-based services (LBS), this paper presents the design of iZone, a mobile social networking system, as well as a prototype implementation. This platform exploits mobile GIS (Geographic Information Systems), LBS and J2ME technologies, combining geographical data to display map on mobile phones. It can provide a number of social networking services via smart phones.