The operation of JET under the EFDA agreement has provided experience in two important areas concerning the future organisation of supra-national Fusion Facilities. The scientific exploitation of the device during 2000 and 2001 has been done by scientists from the different European laboratories, with a significant role of the British UKAEA Association as Operator of the facility. The integration of the operation team with the visiting scientists has been quite successful, not only in the general areas of Tokamak Physics but also in the particular area of Diagnostics, which required a very close collaboration of both groups. In addition to the operation of JET, a complex program to enhance the JET facilities (JET Enhanced Performance) is being prepared and could be implemented during the period 2001-2006. The present paper will briefly discuss the aspects of the 2000-01 operation and enhancements (with emphasis on the diagnostics systems) and give an overall description of longer term enhancement project, focusing on the diagnostics. Given the broad spectrum of the activities described, involving the work of many persons, deep technical details will not be discussed but the author will try to provide a comprehensive list of references when available.