Discrete event simulation technologies have been up and down as global manufacturing industries went through radical changes. The changes have created new problems, challenges and opportunities to the discrete event simulation. On manufacturing applications, it is no longer an isolated model but the distributed modeling and simulation along the supply-chain. In order to study the hybrid manufacturing systems, it is critical to have capability to model human performance with different level of skills and under various working conditions. On service applications, the most critical part is to model knowledge workers and their decision making process. The authors believe that discrete event simulation continue to be one of the most effective decision support tools both in global manufacturing and knowledge economy. There are new opportunities for discrete event simulation such as business intelligence systems and simulation-based education. At the same time, there is a strong need to develop a new generation of discrete event simulation software by taking account of changes in application environments.