Not sure how defunct this blog is, but the following might interest some readers...
It’s an up and coming experiment the ‘Studio Wikitecture’ group is conducting in ‘Second Life’ to explore the potential of applying an open-source paradigm to the design and production of architecture and urban planning.
If interested, this blog post explains the experiment in further detail: http://studiowikitecture.wordpress.com
This video, provides a nice snippet of the technology behind it as well: http://youtube.com/watch?v=Z3eWKIJxzyc