My company (Munich / Germany) is developing a web-two-point-oh-and-whatnot-Wiki based on Ruby, so i'm looking around a bit.
Got to know Wagn from this site, quite a long time ago:
I'm also developing an own Framework for our app. It's called Aurita and is moving pretty fast towards a first final release (well, still have to do some documentation ... ) and already is in real world use at some medium-sized (~100 authors) companies, for intranets and as a website CMS.
It's based on plug-ins and composes GUIs using widget classes (so, not templates).
My Github account is http://github.com/fuchsto
This is also where our open source code is released. Aurita has about 30 plug-ins, but i only released 2 so far.
In case you're interested, i can provide you with full-featured demo accounts for our app. "Show, don't tell", etc. :)