Geant4 is a detector simulation toolkit designed for the new generation of High Energy Physics experiments as well as for nuclear physics, medical and space applications, radiation background studies. Approximately three years since the release of the first Geant4 production version, significant results are already available from many applications of Geant4 in a variety of domains, such as HEP experiments, space and medical applications. New results are produced continuously. An overview of the status of Geant4 and highlight results of its application will be presented.