We currently have just over 35 subscribers. I figure it is time for me to say something.
First of all, thanks for subscribing to the list.
This list started with a conversation that began at Wikimania. When Markus Glaser and I held a MediaWiki meetup one of the recurring themes was Wikifarms.
It seems that farms are relatively common. WikiApiary lists around 100 farms that have just two wikis all the way up to Wikki's 2000+. (WikiApiary is just starting out, so I'll forgive them that they miss Wikia's thousands.)
Despite the wide use of farms, there doesn't seem to be a "standard" way of setting one up. So I've created https://bugzilla.wikimedia.org/52721 ("Create a Wikifarm profile for MediaWiki-Vagrant") that will help us capture the "best practices" way of setting up a wiki farm.
Of course, it would help to have some best practices first. My observation -- please correct me if I'm wrong -- is that there we seem to create MediaWiki ghettos. Developers and administrators in the Wikia ghetto don't communicate (much) with their counterparts in the Wikimedia ghetto or the Semantic MediaWiki ghetto.
So, best practices. MediaWiki-Vagrant and maybe the WikiFarm extension (does anyone use it?).
Maybe we can start the discussion by describing how we set up wikis on our farms?