This page is for notes about giving MediaWiki a distributed computing architecture.
The software is hosted on different servers, all of which are in touch with each other.
By default, changes made on one site are copied by all the others (this shouldn't be hard to do -- periodic polling of the "recent changes" RSS feed by each site lets it know when there is a change, and the data is copied via one of the "?action=" methods (I forget what it's called, but there is one which just returns the raw wikicode).
Each site has a webmaster (who may act solo or may be part of a governance process), and the webmaster can cut off write-access to other sites (in addition to MediaWiki's existing individual user-rights controls) if their edits become too problematic.
Having written several MW extensions, I think I can say with some confidence that this could all be done as a MW extension -- no core code changes needed.
The only problem would be resolving inter-site edit conflicts. I can see at least a couple of ways of dealing with that.