Block copolymers are the focus of a great deal of research activity in contemporary macromolecular science. This is attributable to a range of fascinating fundamental issues associated with understanding self-assembly processes in both solution and in bulk, coupled to an adventitious convergence of substantial progress in synthetic versatility, developments in molecular and structural characterization, understanding of the factors that control phase behavior, and elucidation of the response of copolymer materials to external fields. It is argued that due to the rapid progress in these areas block copolymers now stand on the verge of a new generation of sophisticated materials applications, in which particular nanostructures will play a crucial role. This may be contrasted with the current billion dollar annual market for block copolymer materials, in which no substantial advantage is taken of any particular nanostructure. A variety of persistent challenges are identified that stand between block copolymers and widespread success in novel applications; foremost amongst these are issues concerned with processing.