Recently, Web services have generated great interests in both vendors and researchers. Web services, based on existing Internet protocols and open standards, can provide a flexible solution to the problem of application integration. With the help of WSDL, SOAP, and UDDI, Web services are becoming popular in Web applications. However, the current Web services architectures are confronted with a few stubborn problems, for instance, security. In this paper, we shall give an overview of these problems. We believe that solving these problems will become crucial to success of Web services. In the end, we predict distinct advances in semantic Grid services.