Larry Garfield (aka Crell) provides an update on the "Butler" project, which after this interview was conducted has been accepted by Dries as one of the Drupal 8 core initiatives that has been renamed to be the "Web Services and Context Core Initiative." I interviewed Larry last year at DrupalCon San Francisco after the preliminary discussions for how to better preserve and present the context within Drupal, and there have been a number of architectural discussions on g.d.o. and a Drupal 7 butler module where the development is taking place. He talks a bit about the performance implications, how this helps with mobile distribution, and how he sees that git can help facilitate the parallel development of this functionality since it touches so many different aspects of Drupal core.
Larry always has a big ideas and big plans for the future of Drupal, and has been helping lead the discussions and documentation of this effort at DrupalCon San Francisco, Copenhagen and Chicago. For more information on the four phases of development for implementing the Context, Plugins, REST Services, and Layouts, then be sure to check out Larry's blog post laying out his gameplan.