We would like to thank all the competitors in the 3rd International Planning Competition for contributing their time and enthusiasm to the event we report and for providing the data that has made this paper possible. We would also like to thank Adele Howe who has contributed invaluable advice, comments and huge support and made it possible for this paper to go far further than we could have hoped. We would like to thank David Smith for undertaking the unenviable task of coordinating and editing this special issue of the Journal of Artificial Intelligence Research and doing so with immense patience, good humour and generous support. Finally, we would like to thank Martha Pollack who first proposed the idea of publishing the assembled work in a special issue of the Journal of Artifical Intelligence Research. Her whole-hearted commitment to the project has been vital to its successful conclusion.