Service-oriented architectures have climbed up the path from theory to being widely implemented for use in productive computing environments in both eCommerce and eGovernment. In the latter field of application, new tasks and challenges have arisen from the European Union’s Services Directive, entailing on-demand collaboration of back-office services. Despite the striking success that cooperating web service landscapes have experienced over the last couple of years, there are still serious shortcomings that hinder further propagation of SOAs for collaborative ad-hoc computing scenarios, such as to sufficiently deliver high-quality services in the eGovernment sector. Based on our practical experience in the EU-funded research project Access-eGov, we outline the shortcomings of traditional SOAs, prove the necessity of introducing semantic technologies and show how ontologies and semantically enriched process workflows can be utilised in order to mitigate them.