RFID-Based Systems have started to play a significant role in the automation of many business processes such as ERP systems and object tracking. Several efforts were made within the research community and commercially to enhance the development, deployment and utilization process of these systems. More importantly some research has also started in developing ways to use middleware to facilitate these processes. In this paper we provide an overview of some of the research efforts done and highlight the main issues and challenges of using middleware for RFID systems.