Open Design is a closely related, indeed overlapping open source field of sprawling activity, focused on the whole design world. Architecture, in a sense can be part of Open Design, but so too can software and hardware, desk and table design and 3D printers and CNC routers.
Again, much of the impetus for Open Design is coming from the digital world, but of course is not the origin of free, accessible design. This has been around for aeons, determined by anyone who wants to make their design work available. In the current moment however, open design is growing because of tools, information and capacity to share and discuss amongst the drivers propelling its growth across the planet.
For the curious here are some Open Design links to get juices going :
Making Society Advice on open hardware startups including information on prototyping, manufacturing, selling, distributing, choosing a license, building a community.
Some Open Source Furniture and interior design:
Mozilla Factory Open Source Furniture