The innariddim.com site is now fully functional and now no longer in preview mode. My personal site is now live at joshua.almirun.com (also running on redback).
... are using redback. <a href="http://arthritisaustralia.com.au/">Arthritis Australia</a>, and the <a href="http://preview.innariddim.com/">new version</a> (still in beta, with lorem-ipsum style test content) of my online music magazine Inna Riddim.
Check out the first redback-hosted site (apart from my personal website which is down at the moment anyway because I've changed the engine and haven't changed the data): http://www.itfundforkids.com.au/
We now have support for prefs that are grouped around other prefs, rather than just attached to nodes.