Web services mediation -- the process of bridging disparate service requesters and providers -- is of paramount importance. However, few existing open projects are directly working on service mediation. Although mediation has become an essential part of commercial Enterprise Service Bus (ESB) products, they use proprietary solution, which cannot lead to a high level understanding of the mediation architecture. And the open source ESBs do not really focus on modeling the mediation[1]. After exploring the nature of service mediation problem, this paper presents a systematic evaluation of the support for mediation architecture and patterns in Synapse, a leading Apache open source project that provides a mediation framework for Web services. Based on this evaluation analysis, the paper identifies several interesting mediation research directions and, more importantly, reveals the linkage between Synapse and our ongoing work in providing a distributed web services mediation network.