On Wed, Apr 2, 2014 at 11:09 AM, Sumana Harihareswara <sumanah(a)wikimedia.org
TL;DR: who's testing out the non-Knockout
Besides those listed at 
The Flow discussion system needs to render templates on both the client and
server. The Flow team is going to use handlebars.js and its lightncandy
PHP implementation; we wanted to try KnockOff/TAssembly but the timing
isn't right. We will be ripping off :) MobileFrontend's integration of
Hogan.js client-side templates.
(Gabriel Wicke wrote "I know that for example handlebars is used in a few
teams right now." -- who else?)
oojs - https://www.mediawiki.org/wiki/OOjs_UI
toolkit with one of the other template approaches, or maybe this is
enough by itself!
As I understand it, OOjs UI is more a rich widget library rather than a
templating system. You would compose a page out of widgets that render what
you want, and yes you could use OOjs UI with a templating engine (it
operates on jQuery elements).
Currently used inside VisualEditor and I am not sure
whether any other MediaWiki extensions or teams are using it?
The Multimedia team is using OOjs UI for the "About this file" dialog in
the Media Viewer (currently a beta feature). They haven't styled it to
use Agora controls.
Mobile is using VisualEditor with the beginnings of an Agora theme.
Hope this helps, corrections welcome.
=S Page Features engineer on the Flow team