The capabilities of organizations can be openly exposed, easily searched and discovered, and made readily-accessible to humans and particularly to machines, using service-oriented computing approaches. Artificial intelligence and software engineering researchers alike are tantalized by the promise of ubiquitously discovering and incorporating services into their own business processes (i.e. composition and orchestration). With growing acceptance of service-oriented computing, an emerging area of research is the investigation of technologies that will enable the discovery and composition of web services. The Web Services Challenge (WSC) is a forum where academic and industry researchers can share experiences of developing tools that automate the integration of Web services. In the fourth year (i.e. WSC-08) of the Web Services Challenge, software platforms will address several new composition challenges. Requests and results will be transmitted within SOAP messages. In addition, semantics will be represented as ontologies written in OWL, services will be represented in WSDL, and service orchestrations will be represented in WS-BPEL.