Current developments on Service-oriented Architectures, Peer-to- Peer and Grid computing promise more open and flexible architectures for digital libraries. They will open the Digital Library (DL) technology to a wider clientele, allow faster adaptability and enable the usage of federative models on content and service provision. These technologies raise new challenges for the realization of DL functionalities, which are rooted in the increased heterogeneity of content, services and metadata, in the higher degree of distribution and dynamics, as well as in the omission of a central control instance. This paper discusses these opportunities and challenges for three central types of DL functionality revolving around information access: metadata management, retrieval functionality, and personalization services.