Nice forum, what forum software is mwusers.org running?

[Keith Christian]

Is this software produced by the mediawiki team or is it something else?  Open source?

[kghbln]

It is called "Invision Community" and regrettably not FOSS. See this post to "mediawiki-l".

[Jack Phoenix]

It should be noted that there are several — more or less stable — free and open source software solutions for MediaWiki, such as WikiForum or the (in)famous LiquidThreads. (Mandatory disclaimer: I am one of the authors of WikiForum, although WikiForum has been in a maintenance mode for quite some time and hasn't received any new features and isn't actively being worked on by me or anyone else.)

In addition to that, some sites integrate with an external (FOSS) forum, i.e. wikiHow uses Vanilla Forums for their forums with authentication done by a custom MediaWiki extensions (found in the /extensions/wikihow/Vanilla directory in the wikiHow source code dump); Wikia historically had a phpBB-based forum which even supported wikitext parsing, but this was achieved via various hack to the underlying phpBB codebase, and as such, the code wasn't exactly portable and/or reusable without modifications. That being said, a copy of said hacked phpBB codebase can still be found online (for example, on my GitHub mirror of Wikia's old Google Code account), so if someone were to want to clean up these hacks into a reusable phpBB modification that works on the current phpBB codebase, it's at least theoretically possible.

One of the main issues that basically all of these FOSS forum solutions share is the same: a lack of developers. MediaWiki — as in the core wiki software — is great because it's widely used and has received a lot of attention from developers who use it in varying contexts with varying requirements. Building a forum(-like experience) inside MediaWiki is doable but hard, as witnessed by WikiForum and similar extensions.

In my opinion, the correct way forward would likely be to use MediaWiki for authentication (via OAuth or somesuch) while using an external forum software package for actually implementing the forums. With different modifications, the forum software -- be it phpBB, Vanilla or even the non-free Invision Community -- could be made to support wikitext and whatnot, even.