Here's another pretty picture (and i use the term "pretty" loosely...)
The top diagram shows two bus masters and a web gateway attached to the control network. This control network can be an existing Ethernet or WiFi network, powerline, RS485, or any other network that the master nodes can use to communicate with each other. Each master node drives a network of inexpensive nodes that provide lighting, occupancy information, user interaction, or anything our community develops to control electromechanical contraptions. To the right, the web gateway then connects all of this to a browser or phone app that the user can use to access it. Another option would be an application that can communicate with the maser nodes directly over Ethernet.
One possible candidate for the master node is the Raspberry Pi. This was selected for its mainsream use and ability to bridge the gap between full-featured, scriptable operating systems and embedded hardware like Arduino. The lower diagram shows a Raspberry Pi connected to the control network using Ethernet, and a network of device nodes. An API will be developed to store device information in a database-like format than can be accessed by user scripts, web applications, or the infinite cominations of infinitely diverse products of our users' immaginations.