Peer-to-Peer (P2P) technology is regarded as being disruptive for traditional fixed and mobile operators. However, it can also be considered as an opportunity for new ways of service provisioning. On the one hand, P2P concepts allow a more efficient usage of existing platform resources through relying on existing infrastructure including even the customer equipment and thus provide a cheap service platform. On the other hand, P2P technology brings new business opportunities through extending the service portfolio to user provided services and to ubiquitous environments. Along these lines, we outline in this paper the requirements and building blocks for a P2P based service platform for mobile environments. In addition to P2P lookup and information distribution, these building blocks include reliability, controllability, bootstrapping, reputation management, which address operator specific requirements in particular. Mobile networks pose severe challenges to a P2P service platform in terms of heterogeneous devices and access connections and frequent user joins and leaves. We present a hierarchical P2P system as a core component for a P2P service platform addressing those problems.