Modern large-scale mission-critical systems demand efficient and robust multi-point data dissemination infrastructures. Since such infrastructures have to exhibit good performance when scaling up the number of interacting entities and managing large amounts of data, publish/subscribe services represent a suitable middleware solution due to their decoupling properties. However, since data are conveyed by networks where failures may occur, and since nodes may present a faulty behavior, such services also have to adopt proper mechanisms to deal with several kinds of failures and to guarantee event dissemination despite their occurrence. Although significant efforts have been made on this topic, many issues are still open. This article covers an introduction to the principles of assuring event notification even in the presence of faults, and an analysis of relevant state-of-the-art by both surveying the academic literature over the period 2000-2011 on reliable publish/subscribe services and overviewing current marketed products. Then, it presents the main challenges that are still unresolved and are worth being addressed in future research efforts.