An overview on the "Efficiency of Caching and Content Delivery in Broadband Access Networks" has been published by Gerhard Hasslinger as chapter 4 of a new book on "Advanced Content Delivery, Streaming, and Cloud Services" in the joint IEEE and Wiley Series on Parallel and Distributed Computing. The chapter investigates to which extend transport paths for content via the Internet can be shortened based on distributed CDN caching and server architectures. On the whole, the book provides a balanced summary on current IP content delivery infrastructure from the perspective of content, service and network providers and with regard to the user's quality experience. Among a number of case studies, the final chapter addresses the impact of online social networks, as another contribution in the main focus of the SmartenIT project.