The concept of virtual manufacturing systems (VMS) was proposed more than fifteen years ago and a large number of research and development have been done for realizing VMS. Even with these efforts, VMS has not rearched its effective and practical phase. This report first analyzes the obstacles for realizing VMS in the past research and development, and then describes some emerging technologies which may clear the obstacles and enable industrial applications. Lastly challenges and visions for future VMS research and development are described.