I gave a talk at the Spring ENAR meetings this morning on some of the technical aspects of creating the book. The session was on reproducible research and the slides are here.
I was dinged for not using git for version control (we used dropbox for simplicity) but overall the comments were good. There was a small panel at the end for answering questions, which were mostly related to proprietary systems (e.g. SAS).
I was also approached by an editor for Computational Statistics in regards to writing all of this up, which I will when I get a free moment.