Blended Learning (also known as Hybrid Learning) has currently attracted strong attention specifically at universities. However, Blended Learning because of its dynamic and open nature poses specific requirements on the supporting tools. Tools built on Service-oriented Architectures, if constructed properly, fulfill these requirements best. Based on Web Services, the CEWebS system is being developed at the University of Vienna, Faculty of Informatics. It can provide the students several non-standard services like support for on-line team building, peer-to-peer evaluation of students projects, and other collaborative tools. In the frame of the international cooperation with University of Vienna, the CEWebS framework has already been tested and will be deployed also at Masaryk University, Faculty of Informatics in Brno. It will help to unify the runtime environment for many services that are currently planned, such as several Natural Language Processing or Semantic Web tools, while preserving the freedom of choose of development platform because of web services interoperability.