Honshū, or Honshuu, is the largest island of Japan. It is also the codename for the complete rewrite of of a large distributed SaaS product that has been over a year in the making, embracing a service orientated architecture similar to those popularised by Amazon and Netflix. At the heart of Honshuu is the idea that every service is an island. Any island can talk to another, using strict traditions and customs (REST API), and almost any island can communicate freely with the wider world via intermediaries and guardians of custom (API wrappers, thin layers, and load balancers). Each island is the main land, looking after it's own concerns, only caring that other islands can communicate with it, but not what goes on outside.
This is a cultural shift away from other ways of working more than technological. Knowing when to spin out a new "island" and making sure it can be communicated with in the same fashion as it's neighbours, from common build strategies regardless of base technology, to involving ops as a guiding principle from the very first steps as to how an island should be built.
In day to day practice this means several stand ups (or Google Hangouts) between developers and teams, and maintaining dependency maps between services (islands) and their REST API specifications (like trade agreements between islands), but despite overheads the payoffs in scaling and maintainability can be huge.